YouCute 1to6 Battery Charger for UDI U839 U840 U939 Nano 3D Rc Quadcopter Drone Spare Parts Package included :1 piece of 1 to 6 charger For Udi U839 U840 U939 Nano 3D Rc Over charge protection, Short circuit protection. Light in Green when charging,light off when charge complete Charging 6 batteries at the same time