very good. Very good because it works much better than the original batteries that you find in the helis' kits. just today a 11.1V 1000mAh 25C battery activated 2 or 3 times the protection system of my Esky Honey Bee, where this Storm had not, and did not again when I changed the 1000Ah and put the Storm again to check whether it was a problem of battery or of heli electronics... It is well worth the price, though you can find cheaper batteries. I think that nobody gives nothing for free... ...