I bought H R B 4S 5000 MAH 50C 100C BURST from Amazon $75 each cnd shipped to my door my JAE .21 WAS RUNNING 63 MPH with the Turnigy blue packs put the HRB packs 72 mph off the bat! Stay away from the Giant power lipos from mojo racing bought 2 off them at $115 each us didnt get 2 seasons junk! . Regards Andris Golts.