This Charger takes a standard USB DC5V typical 2A conventional USB power source such as your laptop or AC wall adapter or even your car's USB port. Output voltage: up to DC4.2V 1000mA. Compatible Li-Ion batteries such as 18650 10400 14500 16340 16650 14650 18350 18500 etc rechargeable lithium batteries.

Features: Multi-slot independent charging without interfering with each other, dual-color charging indicator light, red lights when charging, green LED lights when fully charged. Automatic stop when fully charged, and no overcharging. Automatically power off if the battery is reversed to protect it from harm. I tested it and it does go into safe mode if you put them incorrectly.