Best Combo: 2 pcs 3.7V 160mAh 15C LiPo Batteries for Micro Helicopters E-flite MSR /SR/ BMCX with a wall charger (#01316) Used mainly with E-flite MSR /SR helicopter and with E-flite 4-SITE bi-plane and even better with ParkZone Sukhoi 26M 3D plane. Will give more PUNCH and ROBUST performance due to its higher current output and power. Dimensions: 44x12x6mm. Direct replacement, No modification needed! Single cell Li-Polymer 160mAh battery Specially designed for 3.7V MCX battery. This charger can charge up to 2 packs at the same time!