Type: 18650 (or similar size) Lithium-ion (Li-ion) rechargeable battery cell.
Voltage: Nominal 3.7V (fully charged is about 4.2V).
Connection: Has a soldered red (+) and black (-) wire leading to a small JST-style white connector plug.
Common Uses: Small electronics, portable Bluetooth speakers, mini RC toys, backup power packs for small devices, or custom DIY electronics projects.