M3 Fitness Smart band If you’re a fitness freak and love keeping a track of the calories burnt, sleep cycle, and heart rate, and then the M3 Smart Band is what you need. This smart band works as a heart rate tracker, fitness watch, and an activity tracker.M3 waterproof Smart fitness Band compatible with Bluetooth or Heart Rate Sensor. It is compatible to devices having Bluetooth version 4.0 and below in smartphones, Tablets and PC’s and also support Android and IOS. It has features such as calling function which enables you to make a call and disconnect it, you can also send and receive messages through it but only supported to Android Phones for which you need to download app.