Sync: Bluetooth 4.0 wireless technology allows automatic wireless syncing to over 120 smartphones Also syncs to computers and tablets Syncing Distance: 20.0' (6.1 m) Transceiver: Bluetooth 4.0 Water Resistance: Water-resistant to 1 ATM Memory: Tracks 7 days of motion data - minute by minute Tracks daily totals for past 30 days Display: OLED Materials Wristband: flexible, durable elastomer material Clasp: surgical-grade stainless steel Battery Type: Lithium-polymer Battery Life: Up to 7 - 10 days Charge Time: 1 - 2 hours System Requirements: Windows: Windows Vista and later Mac: Mac OS X 10.6 and up Internet connection USB port Operating Temperature : -4 to 113° F (-20 to 45° C) Operating Altitude: 30,000' (9,144 m) Size Fits wrists: 5.5 - 6.5" (14.0 - 16.5 cm) Width of band: 0.8" (2.1 cm) Weight: Not specified by manufacturer Packaging Info Package Weight: 0.3 lb Box Dimensions (LxWxH) 7.8 x 2.8 x 2.8"