Drone Pit Stop 5 X 3.7V 500mAh Li-Po Batteries for UDI Quadcopter (for Models U818A, U818A HD, U818A HD+ 2.4GHz 4, U818A-1) Battery Upgrade 5 X 3.7V 500mAh LiPo Batteries For Models U818A, U818A-1, U818A HD, U818A HD+ 2.4GHz. *Will not fit the "U818A WIFI" Get Extra Juice for a longer flight time. Measurements: 58mm x 17.5mm x 7.8mm Easy Pull feature - easily take the battery out of the drone without pulling the cord. Numbering Space - Dedicated space for battery numbering allows easy management. 100% Satisfaction Guaranteed Or Your Money Back