Griffin Travel Power Bank Backup Battery for Apple Watch - Ultra-Portable Recharging Key Chain for Apple Watch 1050 mAh rechargeable battery provides up to 2.5 full charges for an Apple Watch Certified, MFI-compliant Magnetic Charging surface is built into the battery; no cables to lose Battery charges via any 5-volt USB charger or computer USB port Charge status LED indicator Dimensions: 1.5 (38.1 mm) W X .375 (9.5 mm) D X 4.5 (114.3 mm) H