FEATURES: EDA Scan app detects electrodermal activity Built-in skin temperature sensor High & low heart rate notifications alert Built-in GPS can be used during runs, hikes, rides and more Voice assistant Can make calls from your wrist Fitbit Pay Multi-path optical heart rate sensor Multipurpose electrical sensors compatible with ECG app & EDA app Gyroscope and altimeter 3-axis accelerometer Operating temperature: 14deg to 113degF Maximum operating altitude: 28,000ft SPECS: Small band: fits wrists from 5.5'' to 7.1'' in circumference Large band: fits wrists from 7.1'' to 8.7" in circumference Rechargeable lithium polymer battery Battery life: 6+ days, 10 days Compatible with IOS & Android Water resistant to 50 meters Wireless: Bluetooth 5.0, WiFi, NFC Charging cable included