Lithium Li-Ion 3.7V 14500 AA 800mAh Rechargeable Battery

AA sized battery, known as a 14500 because it it 14mm in diameter and 50mm in length.
It has a voltage of 3.7 and a capacity of 800mAh.

Length: 50mm (suitable for replacing 48mm, 49mm and 51mm long batteries)
Diameter: 14mm
Length: 50mm
Voltage: 3.7V
Typical Capacity: 800mAh
Chemistry: Li-Ion