These are very slim, extremely light weight LiPo batteries. Each cell outputs a nominal 3.7V at 120mAh. Comes terminated with a standard 2-pin JST connector - 2mm spacing between pins, that plugs directly into the battery connector on Altus Metrum flight computers.

Recharge with Altus Metrum Adjustable LiPo charger (not included)

Size: 4x15x30mm, weigh 3.6g

These batteries are ideal for use with TeleMini in airframes as small as 18mm (Estes BT-20, as an example).
WARNING: Unlike most LiPo batteries made for hobby use, these batteries are made specifically for use with Altus Metrum flight computers, and do not contain an over-current protection circuit board!