Mast Rider Pro¡ªNew Revolutionary Model of Mast Rider. Equipped with a 4.0mm stroke and a brushless motor, it offers powerful hitting. The battery under the grip greatly shortens the length of the machine. Being only 92mm in length, even shorter than Mast Racer, and 129g in weight. High-speed charging enables you to work for 4-4.5hrs with only 2.5hrs charging.You¡¯ll also find it super easy to operate this machine with the LED screen that displays the voltage and battery indicator and the 3 buttons used to increase or decrease the voltage, or start/pause the machine.