Good capacity (380 MaH), higher than the original batteries of Hubsan X4 (240), the UAV flies much longer (7-9 min 4-5 against). Heavier also changes a little balance X4, we must review some settings on the remote (in 2 s). Good durability also from my tests (thirty refills to date, no capacity problems). I recommend for the quality, but not too much for delivery, more than 12 days from order receipt (sent from China).