Streamlight 18650 

18650 batteries are most commonly used in rechargeable flashlights, cameras, LED clocks, and portable speakers and fans.

They're also used to build battery packs and power banks such as those found in laptops. The 18650 names is based on their nominal size of 18 mm

• Rechargeable Lithium-Ion Battery
• Integrated Micro USB Port
• Charge Status Indicator
• Integrated Saftey Circuit
• Charger Sold Separately

3.7v 2600mAh Battery Rechargeable in 5 hours, Charges from Strealight AC/USB Sources