The Withings Pulse O2 is a versatile activity and sleep tracker that can be worn on the wrist with a sport band, or clipped on your clothing. The compact tracker also features 4 LEDs which allow you to measure heart rate and blood oxygen level, allowing you to assessthe efficiency of your respiratory function. The touchscreen display allows you to swipe to compare your performance to the past 10 days. The tracker connects wirelessly via Bluetooth Low Energy technology to aggregate and store all your info in your free Withings account and App.