1" Display Screen128 X 128p With Superior Readability In All Light Conditions invertible Screen bluetooth Smart Heart Rate Monitor Includes A Comfortable Soft Fabric Strap That Fits Most Sizes Watch Mode & Activity Mode Convenient Low-profile Design For Ease & Style Activity Mode Connects To A Smartphone Or Device With Bluetooth Connectivity To Stream Information & Data & Control Apps Tracks Steps Distance Calories Burned & Sleep Length & Pattern Water-resistant (ipx7) Ruggedized For Sports Compatible With Iphone 4s Or Later & Select Android Devices With 4.4 Or Later Compatible With Many Leading Fitness Apps Including Strava Mapmyrun Mapmyride Wahoo Fitness & More Ultralow Powernever Requires Recharging 6-month Battery Life On Heavy Usage 11-month Battery Life On Low Usage Requires A 3v Cr2032 Battery gray