The Streamlight SL-B26 (18650) USB Battery (2 Pack) provides an alternate power source for newer Streamlight products that accept either standard CR123A lithium batteries or SL-B26 (18650) batteries. It features an integrated safety circuit that protects from over charging or over discharging. The SL-B26 (18650) battery with integrated micro USB port charges in 5 hours. A wide variety of power sources can be used, such as a PC, power pack or 12VDC automotive power.