7.4V 2S LiPo
1000mAh Capacity
Smart Balance Cable - Requires IMARS charger
If you like to be at the cutting edge of battery technology when it comes to Airsoft, you're going to want to check this out! The Gens Ace 7.4V 25C 1000mAh Airsoft LiPo Battery - Mini-Tamiya is a slim LiPo battery intended for Airsoft buffer tube battery compartments, AK top covers and other cramped spaces requiring a single cell group. The discharge rate is 25C, giving you a snappy response without risking overspin in most setups, and the capacity is 1000mAh, meaning you might need two to get through a full game day. 
Where this battery differs from the norm is its Smart Balance Connector which interfaces with the Gens Ace IMARS Mini Charger, communicating the battery type and current charge levels and immediately commencing optimal charging as soon as this "Smart Battery" is connected. Compared to legacy smart chargers, this saves loads of time but unfortunately means that this battery cannot be charged using a standard LiPo balance charger.