18650 Li-Ion battery, commonly used in LED torches.

Specifications
DC Voltage : 3.7V
Dimensions: 65 x 18 mm
UN Number : 3480
Battery Chemical Composition : Lithium Ion

NOTE: For shipment by road transport only.

NOTE: This is an unprotected rechargeable lithium battery (Li-Ion or LiFePO4) which is only suitable for use in a compatible device/charger.
Use of a unprotected cell where a protected cell is expected is very dangerous, please review your product's user manual before proceeding.