Battery reached the end of its cycle life? Need that high setting but a single battery can't last long enough? Solve problems like these with the STEELMAN PRO 60660 Rechargeable 18650 Li-Ion 3.7V 2200mAh Replacement / Backup Battery. This lightweight power cell can replace either a dying battery whose charge cycles are used up or can be easily carried in a pocket or work bag and swapped out when the current battery's charge runs low so you can keep going longer. Designed with Li-Ion technology, this battery provides high energy density along with fast and efficient charging and a low self-discharge rate so they will always be ready for use. Compatible with the STEELMAN PRO 60720 Slim-Profile Motion-Activated Headlamp, for other STEELMAN lights and headlamps, see STEELMAN 78626.