30a bidirectional brushless esc 2-4s ubec 5v 2a electric speed controller for remote control car pneumatic underwater high current bidirectional ubec for 2-4s lipo batteries in rc helicopters for fpv drones and racing quadcopters - rs731730a bidirectional brushless esc 2-4s ubec 5v 2a electric speed controller for remote control car pneumatic underwater high current bidirectional ubec for 2-4s lipo batteries in rc helicopters for fpv drones and racing quadcopters - rs7317