Tenergy 7.4v 1000mAh 20C Airsoft LiPo Battery

"battery works great for me have had this battery for almost a yr now and it never fails me, would buy another, just make sure you kno how to properly charge lipos or u will ruin them quickly

"I would stay away from these. I have two and have had problems with both of them. For the first one, I had it for about one month before one of the cells died, so now it can't hold a charge and is therefore unusable (and dangerous, too). For the second one, I also had it for about a month before it melted my gun's Tamiya connector, so now they're fused together.

Pros
High rate of fire
Wiring seems solid
Small and compact
Lightweight

Cons
Short battery life (if you shoot a lot during games, this won't last very long)
I had problems with mine, so reliability is iffy
Neither lasted more than a month for me