Fly Kool 3.7V 850mAh 20C lipo battery for SYMA X56W MJX Mini Quadcopter 5Pcs 3.7V 850mAh 20C Lipo Battery Compatible for:Syma X56W MJX Quadcopter Product size:50*30*7mm/2.00*1.18*0.27 inch Warranty: 6 Month Warranty. We provide friendly after-sale service and no risk refund for our customers. If you have any issue,please contact us and we will try out best to slove your issue!