7.4v 850mAh Red Tiger Battery (LiPo). A very small size battery. Specifically made to fit in odd sized guns and PEQ mounted boxes. We got it to fit in the smallest "PEQ battery boxes" we sell, along with larger ones too. It may get in some other stocks, handguards, and others that require a small square/rectangle battery fit.Your choice of plug type: standard mini-Tamiya or T-Plug (Deans) - use drop-down menu to select option. If you're not sure which plug type to use, get the mini-Tamiya, which is the standard for all airsoft guns. The T-Plug is a custom configuration for advanced users only. Uses standard Lipo balance charger connection for charging. This a solid battery that will give you a ton of power and voltage for your gun.See Technical Specs Tab for warnings and charging information. Requires LiPo specific charger.