DSEE restores high frequency sounds lost in compression. Up to 10hr battery life, total up to 20hr with charging case. Splash-proof and sweat-proof with an IPX4 rating. Easier, clearer hands-free calling. Small and light for a great fit and all day wear. Ergonomic Surface Design conforms to most ear shapes. Fine-tune your sound using the Sony | Headphones Connect app. Optional use of one earbud only. Easy button operation to take control without your phone. Experience 360 Reality Audio for a truly immersive experience.