Myzone [Standard Accessories] ・MZ-Switch unit ・Chest, forearm, and wrist straps (3 total) ・USB cable ・Quick Start Guide Comes as a boxed set. App Connectivity 99.4% accuracy using a chest-based ECG sensor, the same technology used by medical professionals 95% accuracy using wrist and arm PPG sensors Connectivity Bluetooth ANT+ Durability Waterproof: Up to 10m depth Battery Charging interval: 3-6 months *Varies depending on usage.