Guard Dog Security Dual Smart Battery Charger with USB Input DUAL BATTERY CHARGER: The convenient portable battery charger has slots to power up 2 rechargeable batteries, and auto selects the appropriate charging voltage. USB PORT: Along with recharging batteries, the USB battery charger features a port on the side, smart charging your USB devices at the same time. CAR OR HOME CHARGER: The electronic battery charger operates on either 100-240vac for home use or 12Vdc for use in vehicles, and has LED indicator lights to show charge. ADVANCED CHARGER: The smart battery charger is compatible with AA, AAA, aaaa, c, A23, cry and mar/li-ion batteries: cars, 26650, 18650, 17670, 18490, 17500, 17335, 16340 (Rcr123), 14500, 10440. 100% SATISFACTION: If youre not happy with your Guard Dog Dual Battery Charger, just swap it out for another, no questions asked!