The Mi Smart Band 4 features a 39.9% larger (than Mi Band 3) AMOLED color full-touch display with adjustable brightness, so everything is clear as can be. Compatible with Android 4.4 or later/iOS 9.0 or later With music control on the band you can change the song, increase/decrease the volume and groove on without even touching your phone With a sturdy 5ATM waterproof built, you can now take your band for a swim. It auto detects your swim style and captures 12 detailed data points for tracking. Connectivity - Bluetooth 5.0 Health and wellness tracking at its best with 24/7 automatic heart rating monitoring and alerts to warn you when the heart rate is high Style the band display as per your mood with unlimited watch faces. Simply pick a photo from your gallery and set it as your watch face With the band on your wrist, you can receive text messages, silence or reject calls, and get social media notifications instantly Up to 20 days of long lasting battery life for uninterrupted performance