Refurbished Apple Watches

Name: Refurbished Apple Watches
Brand: Back Market
Price: 288 USD
Availability: InStock
Rating: 4.36 (16453 reviews)

Thanks to sophisticated biometric processors and always-on Retina display, the refurbished Apple Watch delivers meticulous health tracking. Its Apple ecosystem integration and all-day battery make it an essential choice....

Compare devices

19 products

Trade in to get it for less

Today’s purchase could set you back a lot less when you trade in an old device at the same time.

Apple Watch Ultra

(300)

Starting at

Refurbished price:$288.00

Versus $799.99 new

Apple Watch Series 7

(1,509)

Starting at

Refurbished price:$120.74

Versus $499.00 new

+4 more colors

Apple Watch Series 3

(1,632)

Starting at

Refurbished price:$77.01

Versus $299.00 new

+1 more colors

Apple Watch Series 10

(350)

Starting at

Refurbished price:$228.00

Versus $399.00 new

+2 more colors

Apple Watch Series 11

(211)

Starting at

Refurbished price:$295.00

Versus $399.00 new

+3 more colors

Apple Watch Series 9

(534)

Starting at

Refurbished price:$183.74

Versus $400.00 new

+3 more colors

Apple Watch Series 8

(779)

Starting at

Refurbished price:$149.00

Versus $599.99 new

+2 more colors

Apple Watch SE Series 2

(1,267)

Starting at

Refurbished price:$132.70

Versus $499.99 new

Apple Watch Series 11

(176)

Starting at

Refurbished price:$319.95

Versus $499.00 new

Apple Watch Series 6

(1,453)

Starting at

Refurbished price:$96.00

Versus $429.00 new

+2 more colors

Apple Watch Ultra 3

(19)

Starting at

Refurbished price:$620.00

Versus $799.00 new

Apple Watch Ultra 2

(167)

Starting at

Refurbished price:$426.00

Versus $899.00 new

Apple Watch SE Series 3

(119)

Starting at

Refurbished price:$196.00

Versus $299.00 new

Apple Watch Series 7

(1,496)

Starting at

Refurbished price:$159.00

Versus $529.00 new

+4 more colors

Apple Watch SE Series 1

(925)

Starting at

Refurbished price:$109.00

Versus $309.00 new

Apple Watch Series 4

(937)

Starting at

Refurbished price:$124.99

Versus $415.00 new

Apple Watch SE Series 2

(1,238)

Starting at

Refurbished price:$194.99

Versus $329.00 new

Apple Watch Series 6

(1,412)

Starting at

Refurbished price:$199.00

Versus $429.00 new

Apple Watch Series 5

(1,906)

Starting at

Refurbished price:$130.00

Versus $799.00 new

Apple Watches deals

Price drop
Apple Watch Series 10Premium • 42mm • Aluminium • Rose Gold • GPS + Cellular
(421)
Refurbished price:$368.00
Save $45.00
Last lowest price : $413.00
The lowest price for this product in this exact configuration on Back Market in the 30 days prior to 7/20/2026. This reference will update on 7/27/2026.
Price drop
Apple Watch Ultra 3Premium • 49mm • Titanium • Black • GPS + Cellular
(19)
Refurbished price:$629.00
Save $42.00
Last lowest price : $671.00
The lowest price for this product in this exact configuration on Back Market in the 30 days prior to 7/20/2026. This reference will update on 7/27/2026.
Price drop
Apple Watch Series 6Fair • 40mm • Stainless steel • Graphite • GPS + Cellular
(1,432)
Refurbished price:$114.95
Save $7.05
Last lowest price : $122.00
The lowest price for this product in this exact configuration on Back Market in the 30 days prior to 7/20/2026. This reference will update on 7/27/2026.
Price drop
Apple Watch Series 9Fair • 45mm • Stainless steel • Graphite • GPS + Cellular
(480)
Refurbished price:$188.00
Save $11.95
Last lowest price : $199.95
The lowest price for this product in this exact configuration on Back Market in the 30 days prior to 7/20/2026. This reference will update on 7/27/2026.
Price drop
Apple Watch Series 11Premium • 46mm • Aluminium • Rose Gold • GPS + Cellular
(209)
Refurbished price:$350.00
Save $29.00
Last lowest price : $379.00
The lowest price for this product in this exact configuration on Back Market in the 30 days prior to 7/20/2026. This reference will update on 7/27/2026.

Apple Watches

Apple Watch Series 11 colors guide: find the perfect match for your personal style | Back Market

Explore the Apple Watch Series 11 colors and learn which finishes Apple offers, why certain colors are popular, and get the best shopping tips.

Customer reviews for Refurbished Apple Watches

Overall rating

16,453 verified reviews

Rating details

Appearance
4.3/5
Overall performance
4.3/5
Packaging
4.5/5
Shipping
4.6/5

Reviews

Oleg B.
Verified purchase
Reviewed 3/17/26, United States.
I recently purchased a refurbished Apple Watch Ultra 2 and I'm genuinely impressed—it's been an excellent buy! The watch arrived in very good condition overall. The titanium case looks sharp with no noticeable scratches or dents, the crystal-clear display is pristine, and both the Digital Crown and side button feel smooth and responsive, just like new. The whole unit gives off that premium, rugged Ultra vibe without any signs of heavy prior use. What really stands out is the battery health at 97%—that's outstanding for a refurbished unit! It easily lasts a full day (and often into the next) with heavy GPS tracking, workouts, notifications, and always-on display enabled. The only minor suggestion I'd make to the reseller is to include information about whether the previous owner was a smoker or non-smoker. Even though this particular watch has zero odor or residue issues (it smells completely clean and fresh), knowing that detail upfront would help buyers who are extra sensitive to any potential lingering smells make a more confident choice. Overall, highly recommended! If you're looking for a top-tier rugged smartwatch at a better price point without sacrificing much (if any) performance or condition, this refurbished Apple Watch Ultra 2 is a fantastic option. Great value and I'm thrilled with it. 5 stars!
Apple Watch Ultra 2 (2023) GPS + Cellular 49 mm - Titanium Natural Titanium - Alpine loop Blue
Apple Watch Ultra 2 (2023) GPS + Cellular 49 mm - Titanium Natural Titanium - Alpine loop Blue
See item
Condition
Premium
Close to perfection. The body may have tiny micro-scratches. For items with screens, the screen will be flawless.
Purchased
3/3/26
Slava V.
Verified purchase
Reviewed 7/9/26, United States.
The watch arrived quickly and was packaged well. After inspecting it, I found only one tiny cosmetic imperfection that was barely noticeable, which was impressive considering it was listed in excellent condition. My biggest concern was the battery life since it was a refurbished device, but it exceeded my expectations. I was able to get about 2½ days of use on a single charge, compared to Apple’s advertised 36 hours. Overall, I’m very happy with the watch and the money I saved. The included watch band was an aftermarket band, but it was surprisingly decent and exactly what I expected for a refurbished purchase.
Apple Watch Ultra 2 (2024) GPS + Cellular 49 mm - Titanium Black - Trail loop Black
Apple Watch Ultra 2 (2024) GPS + Cellular 49 mm - Titanium Black - Trail loop Black
See item
Condition
Excellent
Almost no signs of wear. The body may have very light micro-scratches. For items with screens, the screen will have no scratches.
Purchased
6/5/26
Angel A.
Verified purchase
Reviewed 6/28/26, United States.
⭐⭐⭐⭐⭐ Absolutely flawless — feels brand new! I was a little hesitant to buy a refurbished Apple Watch, but Back Market completely blew me away. I ordered the Apple Watch SE 3, and honestly, if it didn't come in a generic box, I would have sworn it came straight from Apple. The screen is pristine, the battery health is excellent, and it functions perfectly. Saving a chunk of cash while getting a device that looks and operates like it's brand new is a massive win. Shipping was fast and the packaging was super secure. I'm officially hooked on buying refurbished now. Highly recommend!
Apple Watch Series SE 3 (2025) GPS + Cellular 44 mm - Aluminium Midnight
Apple Watch Series SE 3 (2025) GPS + Cellular 44 mm - Aluminium Midnight
See item
Condition
Excellent
Almost no signs of wear. The body may have very light micro-scratches. For items with screens, the screen will have no scratches.
Purchased
6/19/26
Benjamin R.
Verified purchase
Reviewed 6/18/26, United States.
I loved how I almost looked brand new but after I cleaned it up, I can’t tell a difference between a new one and mine. The one bonus to it was I know that this Apple Watch Ultra 2 was from overseas because the blood oxygen sensor works where if it was from the United States I wouldn’t have that feature
Apple Watch Ultra 2 (2023) GPS + Cellular 49 mm - Titanium Natural Titanium - Trail loop Black
Apple Watch Ultra 2 (2023) GPS + Cellular 49 mm - Titanium Natural Titanium - Trail loop Black
See item
Condition
Fair
Signs of wear. The body may have a few visible scratches and dents. Items with screens may have light scratches.
Purchased
6/4/26
Nevaeh R.
Verified purchase
Reviewed 3/14/26, United States.
I bought the Apple Watch Series 6 in excellent condition, and it truly lives up to that description. The watch arrived in great shape, it feels brand new. Everything works perfectly, performance is smooth, and the battery life is exactly what I expected.
Apple Watch Series 6 (2020) GPS + Cellular 44 mm - Aluminium Space Gray
Apple Watch Series 6 (2020) GPS + Cellular 44 mm - Aluminium Space Gray
See item
Condition
Excellent
Almost no signs of wear. The body may have very light micro-scratches. For items with screens, the screen will have no scratches.
Purchased
2/27/26
Ulises P.
Verified purchase
Reviewed 2/26/26, United States.
Everything was perfect from start to finish. The Apple Watch Ultra arrived in great condition, exactly as described. It works flawlessly, the battery life is strong, and the cosmetic condition is very well maintained. Setup was quick and easy with no issues at all. I’m very satisfied with this purchase and would definitely buy again. Highly recommended!
Apple Watch Ultra (2022) GPS + Cellular 49 mm - Titanium Natural Titanium
Apple Watch Ultra (2022) GPS + Cellular 49 mm - Titanium Natural Titanium
See item
Condition
Good
Light signs of wear. The body may have light micro-scratches. For items with screens, the screen will have no scratches.
Purchased
1/28/26
Nill D.
Verified purchase
Reviewed 2/4/26, United States.
I bought the Apple Watch Series 10 in excellent condition, and it truly lives up to that description. The watch arrived in great shape, with no noticeable marks or signs of wear, and it feels almost like new. Everything works perfectly, performance is smooth, and the battery life is exactly what I expected.
Apple Watch Series 10 (2024) GPS + Cellular 42 mm - Aluminium Jet Black
Apple Watch Series 10 (2024) GPS + Cellular 42 mm - Aluminium Jet Black
See item
Condition
Excellent
Almost no signs of wear. The body may have very light micro-scratches. For items with screens, the screen will have no scratches.
Purchased
1/20/26
Ashlee S.
Verified purchase
Reviewed 7/15/26, United States.
We love this device! I wanted to get my husband an Apple Watch to track his fitness and this worked out perfectly. For those wondering about battery health when buying from BackMarket, our experience was splendid; the battery health was at 100%! I don’t think this watch has ever been used. 1000/10 will be coming back to BackMarket!
Apple Watch Series SE 2 (2022) GPS + Cellular 44 mm - Aluminium Midnight
Apple Watch Series SE 2 (2022) GPS + Cellular 44 mm - Aluminium Midnight
See item
Condition
Excellent
Almost no signs of wear. The body may have very light micro-scratches. For items with screens, the screen will have no scratches.
Purchased
7/8/26
Alexandra S.
Verified purchase
Reviewed 7/10/26, United States.
The watch I received is perfection and impossible to differentiate from a new from the box at the Apple Store. The website was easy to navigate, find and compare models, and up front clear pricing. Once purchased the watch was processed right away and dispatched via FedEx. All in all an exceptional purchasing experience and Back Market will likely be my first stop when looking to add or upgrade any of my digital devices. Very highly recommend!
Apple Watch Series SE 3 (2025) GPS + Cellular 40 mm - Aluminium Starlight
Apple Watch Series SE 3 (2025) GPS + Cellular 40 mm - Aluminium Starlight
See item
Condition
Premium
Close to perfection. The body may have tiny micro-scratches. For items with screens, the screen will be flawless.
Purchased
6/12/26
Leilah K.
Verified purchase
Reviewed 6/10/26, United States.
I recently bought an Apple Watch from Back Market and I am absolutely loving it! Having bought from them before, I knew exactly what to expect and they delivered once again. The watch arrived in perfect condition, truly as good as new, with everything functioning flawlessly right out of the box. If you have not tried Back Market yet, you are missing out. Highly recommend!
Apple Watch Series 6 (2020) GPS + Cellular 44 mm - Stainless steel Silver
Apple Watch Series 6 (2020) GPS + Cellular 44 mm - Stainless steel Silver
See item
Condition
Good
Light signs of wear. The body may have light micro-scratches. For items with screens, the screen will have no scratches.
Purchased
5/18/26

Read our guides

Our recent comparisons

Comparison
iPhone 14 Pro Max • Locked T-Mobile vs Motorola Moto G (2024) • Unlocked comparison

Searches so popular you can't sit with them

Father's Day Fossil Watches DJI Drones AirTag Garmin watches Student Discount Apple Watch Ultra Amazfit Playstation Accessories Apple Watch Series 3

Apple Watches deliver comprehensive health monitoring and seamless iPhone integration across designs ranging from everyday fitness tracking to extreme adventure capability. Choosing a refurbished smartwatch gives you access to Apple's wellness ecosystem while making an environmentally conscious decision. Find the Apple Watch that matches your lifestyle from casual wellness tracking to demanding outdoor pursuits.

What are the key features of Apple Watches?

Advanced health sensors: ECG capability, blood oxygen monitoring, heart rate tracking, and temperature sensing
Comprehensive wellness tracking: sleep analysis with sleep stages, cycle tracking, and medication reminders
Safety features: fall detection, crash detection, and Emergency SOS with international calling
Always-On Retina display: screen remains visible when your wrist is down across the lineup
Built-in GPS: accurate outdoor tracking for running, cycling, and walking without your iPhone
Water resistant: 50-100 meter ratings for swimming and water sports depending on model
Apple ecosystem integration: seamless connection with iPhone, AirPods, Apple Pay, and Apple services
Fitness tracking: comprehensive workout modes with detailed metrics and Activity Rings
iPhone compatibility: requires iPhone XS or later running iOS 17 or higher (varies by model)

What are the differences between a refurbished and a used Apple Watch?

A used Apple Watch is resold without professional inspection or warranty. Health sensors including ECG, temperature sensing, and blood oxygen monitoring can degrade from daily wear. Water resistance seals may be compromised, and battery health often suffers from charging cycles. A refurbished Apple Watch from Back Market has been thoroughly tested by trusted refurbishers following our Quality Charter.

Each watch undergoes comprehensive inspection of all health sensors (ECG, blood oxygen, temperature, heart rate), GPS accuracy, display condition and brightness, Digital Crown and button operation, battery health, water resistance seal integrity, charging capability, and overall functionality. Every device comes with a minimum 1-year warranty and 30-day returns. You get Apple's advanced health tracking without premium pricing, while reducing electronic waste.

Who are Apple Watches best for?

Apple Watches serve diverse iPhone users across different activity levels:

iPhone users wanting comprehensive health tracking: ECG, blood oxygen, temperature sensing, and detailed wellness insights
Fitness enthusiasts: accurate GPS tracking, comprehensive workout modes, and training metrics support active lifestyles
People prioritizing safety features: fall detection, crash detection, and Emergency SOS provide peace of mind
Outdoor adventurers and athletes: Apple Watch Ultra's rugged design and extended battery handle demanding activities
Health-conscious individuals: cardiovascular monitoring, sleep tracking, and medication reminders support proactive wellness
Apple ecosystem users: seamless integration with iPhone, AirPods, Mac, and other Apple devices
Users wanting the latest technology: cutting-edge sensors and features as Apple releases them

Which Apple Watch should you choose?

Apple Watch Ultra is the premium adventure watch engineered for extreme conditions and serious outdoor athletes. The titanium case with sapphire crystal provides maximum durability against impacts and scratches. Battery life extends to 36 hours normal use, 60 hours in Low Power Mode—far exceeding standard Apple Watch models. The 49mm display is the brightest Apple offers, readable even on glaciers and open water. The Action Button provides customizable quick access to workouts, compass waypoints, dive modes, or other functions. Dual-frequency GPS (L1 and L5) delivers superior accuracy in challenging environments. The Ultra is certified for recreational diving to 40 meters with the Oceanic+ app. The siren feature (86 decibels) helps attract attention in emergencies. Choose the Apple Watch Ultra if you're a mountaineer, trail runner, triathlete, diver, or adventure athlete needing maximum durability, extended battery, and specialized features for demanding pursuits.

Apple Watch Series 10 represents the latest mainstream flagship with cutting-edge health sensors, fastest processor performance, and newest watchOS features. Building on the Series 9 foundation, the Series 10 would include advanced health monitoring like ECG, blood oxygen, temperature sensing, and comprehensive sleep tracking with potential new wellness capabilities. Expect the S10 chip for fastest performance, improved battery efficiency, and possibly enhanced display technology. Available in 42mm and 45mm sizes (or Apple's latest sizing) for different wrist preferences. The Series 10 would feature double tap gesture control, on-device Siri processing, and the brightest display among standard Apple Watch models. Choose the Apple Watch Series 10 if you want the absolute latest Apple health tracking technology, longest software support ahead, and cutting-edge features as Apple releases them in their mainstream design.

Apple Watch Series 11 would represent Apple's next-generation innovation with anticipated advances in health sensing, battery technology, and display capabilities. Expected improvements might include enhanced battery life, new health sensors, refined design, faster charging, or breakthrough features Apple hasn't yet announced. It would include all established Apple Watch features: ECG, blood oxygen, temperature sensing, crash detection, fall detection, comprehensive fitness tracking, and Always-On Retina display. As the newest model, it would guarantee the longest software support with watchOS updates for years ahead. Choose the Apple Watch Series 11 if you want to future-proof your purchase with the newest technology Apple offers, longest update support, and innovations that define the next era of Apple Watch capability.

Buy refurbished Apple Watches at the best price on Back Market

Back Market offers refurbished Apple Watches at competitive prices with verified health tracking accuracy and performance. Each watch is:

Tested by trusted refurbishers: ECG, temperature sensing, blood oxygen, GPS, Action Button (Ultra), and all features verified working
Backed by warranty: minimum 1-year coverage protects your investment in premium Apple technology
Returnable for 30 days: test it through workouts, outdoor activities, and daily use to ensure it meets your needs
Better for the environment: choosing refurbished reduces e-waste and extends the life of quality wearable technology

Browse models including Apple Watch Ultra for adventure, Series 10 for cutting-edge features, and Series 11 for the newest innovations. Different cosmetic grades from Premium to Fair let you prioritize appearance or value. Choose between sizes, materials (aluminum, stainless steel, titanium), and GPS or GPS + Cellular connectivity to get Apple's health monitoring at refurbished pricing.

What makes the Apple Watch Ultra different from standard Apple Watches?

The Apple Watch Ultra is built for extreme conditions with a titanium case instead of aluminum, providing superior durability. Battery life nearly doubles—36 hours normal use versus 18 hours on standard models, with Low Power Mode extending to 60 hours for multi-day adventures. The 49mm display is significantly larger and brighter (up to 2000 nits) than standard models. The Action Button provides customizable physical control—crucial when wearing gloves or during activities. Dual-frequency GPS delivers measurably better accuracy on complex routes. The Ultra is certified for diving to 40 meters with depth gauge and dive computer functionality. The emergency siren is audible up to 600 feet. Choose Ultra for demanding outdoor pursuits, ultra-endurance events, or maximum durability. Choose standard Series models for everyday fitness, health tracking, and comfortable daily wear.

Do all Apple Watches have Always-On Display?

Yes, all current Apple Watch models from Series 5 onward include Always-On Retina display—Series 10, Series 11, and Apple Watch Ultra all feature this technology. The screen remains visible at dimmed brightness when your wrist is down, showing time and complications without raising your wrist. When you raise your wrist or tap the display, it brightens to full intensity. Always-On Display provides traditional watch behavior while maintaining Apple Watch's battery efficiency. Older models (Series 3, 4) and the Apple Watch SE do not have Always-On Display—the screen turns off when your wrist is down.

What's the battery life on different Apple Watch models?

Battery life varies significantly by model. Standard Apple Watch models (Series 10, 11) provide up to 18 hours of typical use with Always-On Display, notifications, workouts, and health monitoring. Heavy GPS use during long runs drains battery faster—continuous GPS tracking lasts 6-8 hours. The Apple Watch Ultra extends dramatically to 36 hours normal use and 60 hours in Low Power Mode. During continuous GPS workouts, the Ultra lasts roughly 12 hours in normal mode. Fast charging helps—Series models reach 80% in about 45 minutes, Ultra charges similarly. Most standard Apple Watch users charge nightly, while Ultra users charge every 1.5-2 days with typical use or before multi-day adventures.

Can I use Apple Watch for diving?

Only the Apple Watch Ultra is certified for recreational scuba diving to 40 meters (130 feet) and meets EN13319 dive computer standards. Using the Oceanic+ app (subscription required), the Ultra functions as a dive computer showing depth, time, ascent rate, safety stops, and no-decompression limits. Standard Apple Watch models (Series 10, 11) are water-resistant to 50 meters for swimming and water sports but are not dive-rated or certified for scuba diving. You can swim, snorkel, and do surface water sports with standard models, but for scuba diving, the Apple Watch Ultra is the only option in Apple's lineup.

How accurate is GPS on Apple Watch Ultra vs standard models?

The Apple Watch Ultra uses dual-frequency GPS (L1 and L5 satellite signals), which significantly improves accuracy in challenging environments. In dense forests, urban canyons with tall buildings, and mountainous terrain where standard GPS struggles, the Ultra maintains better satellite lock and more accurate positioning. Standard Apple Watch models (Series 10, 11) use single-frequency GPS with GLONASS and Galileo support—accurate for most running and cycling but less precise in technical terrain. For road running in open areas, the difference is minimal. For trail running, mountaineering, or ultra-endurance events on complex courses, the Ultra's GPS accuracy advantage is noticeable and valuable.

Do Apple Watches work with Android phones?

No, all Apple Watches require an iPhone to set up and use. They only work within the Apple ecosystem and won't pair with Android devices. You need an iPhone XS or later (specific iOS version varies by watch model) to use any Apple Watch. Apple Watches are designed for deep integration with iPhone, AirPods, Apple Pay, and other Apple services. If you have an Android phone, consider Samsung Galaxy Watch, Google Pixel Watch, Garmin, or other Wear OS smartwatches designed for Android compatibility.

What is the Action Button on Apple Watch Ultra?

The Action Button is a customizable physical orange button on the left side of the Apple Watch Ultra case. By default, it starts workouts, but you can customize it to trigger other functions: start a dive, mark compass waypoints, begin a backtrack navigation, activate the flashlight, start a stopwatch, or run shortcuts. During workouts, pressing it marks segments or transitions between multisport activities. The physical button works reliably when wearing gloves, when hands are wet, in extreme cold, or in conditions where touchscreens become difficult to use. It's one of the Ultra's most practical features for outdoor athletes and adventurers.

Which Apple Watch has the longest battery life?

The Apple Watch Ultra has the longest battery life in Apple's lineup—up to 36 hours in normal use and 60 hours in Low Power Mode. This nearly doubles the standard Apple Watch battery life. For GPS workouts, the Ultra lasts approximately 12 hours in continuous GPS mode. Standard Apple Watch models (Series 10, 11, 9, 8) all provide roughly 18 hours of typical use. If you need multi-day battery for backpacking, thru-hiking, ultra-marathons, or simply don't want to charge daily, the Apple Watch Ultra is the clear choice. For typical daily use with nightly charging, standard models work perfectly well.

Choose location

Suggested searches

Popular searches

Refurbished Apple Watches

Trade in to get it for less

Apple Watches deals

Apple Watch Series 11 colors guide: find the perfect match for your personal style | Back Market

Reviews

Oleg B.

Slava V.

Angel A.

Benjamin R.

Nevaeh R.

Ulises P.

Nill D.

Ashlee S.

Alexandra S.

Leilah K.

The Apple Watch Ultra 3 vs. Apple Watch Ultra 2: two heavyweights compared | Back Market

Apple Watch SE 3 colors: fewer choices, superb finishing | Back Market

Apple Watch SE 3 vs. Apple Watch SE 2: sorry SE 2, SE 3 wins this round | Back Market

Apple Watch Ultra 3 colors: classic elegance or modern tech appeal | Back Market

Is the 1st Gen Apple Watch Still Good? | Back Market

Apple Watch 11 review: A spec bump in the right direction | Back Market

iPhone 14 Pro Max • Locked T-Mobile vs Motorola Moto G (2024) • Unlocked comparison