This thing is awsome! I got it for my JG 6604 M4 and I'm pretty sure it increased my fps by about 10-20 and it increased my RPM by at least 100-200 rounds. Like the guy before me said, the battery came in a TSD bag but it is an Intellect battery inside, and the battery is slightly harder to get in but not a problem. If you need a new battery, GET THIS ONE. You won't be disappointed. It is only $2 more than the 1200 mah battery and it is an intellect. Also, I recommend getting a smart charger because I fried my stock battery and that is why I got this one.
Increases ROF(rate of fire for those of you who don't know)
Increases FPS a little
Cheap but good quality
A little bit harder to get in, but don't let that stop you from getting it
Rating: [5 of 5 Stars!]