For: Echo 1 11.1v 1100mAh LiPo Mini Battery Package (Battery, Charger & Liposack)Product Information:
I have had this battery for about 8 months now, and it has not failed me once. The 15c output is a great medium between 12c and 20c. On my stock G4, it was giving me about 19 rps, which is not bad at all for a stock combat machine. It's also very small, so it'll fit in most buffer tubes with no problem at all. With the standard crane stock on most G4s, you can fit the lipo in there and still have enough space to contract the stock to its least position without pinching wires. However, know that if you want to fit this battery into a buffer tube without a crane stock, the standard G&G buffer tube will be too tight to accept it. Make sure you get a new buffer tube if you have a g4 or else this battery will not fit.
Not TOO expensive
Hasn't blown up yet
Lipos are not to be taken lightly (not really a con, I just wanted to put something in here)