Xiaomi wristband - A Fitness Tracker, Sleep Tracker, Call Reminder! 

- waterproof 
- environment test
- boothtooth for Android iOS - Apple

Check out this must have wristband at DHGate! This is the original site wear they are sold. Beware of the other sites that may sell knockoffs. For new customers a $50 coupon when they spend $200 or more on their first order, valid though 31st, May, 2015, no promotion code needed.