Streamlight - Battery Chargers; Battery Size Compatibility: 3.7V; Battery Chemistry Compatibility: Lithium-Ion; Charging Time (Hours): 3.50; Charging Time (Minutes): 210; Maximum Number of Batteries: 2; Voltage: 3.70; Includes: 120V AC Adapter; USB
Streamlight 18650 USB Rechargeable Lithium-Ion Battery 22101 B&H
Everything You Need to Know About the 18650 Battery
How to calculate the real charge and run time of a 18650 battery? - Project Guidance - Arduino Forum