Revolution of stucture: the battery of Mast Rider machine is in the grip aim to shorter the length of machine. Shorter length and better feeling. Shorter length with lighter weight: Only?112mm?length and?151g weight makes it more comfortable to use and operate while tattooing.?Larger Battery Capacity: Battery volume is 1520mAh, working time of machine is 4-6 hrs and charging time is 3hrs.?LED screen : To protect your eyes. Voltage and battery capacity timing in the screen. The machine shell made by aluminium alloy.? 3 buttons on the machine -- How to use: "+" increase voltage, "-"decrease voltage, "??" start or pause machine.Specifications: Weight: 151G Diameter: 33MM Length: 112MM Stroke: 3.5MM Working Voltage: 5-12V Motor Type: Brushless Motor Speed: 12V/9000 RPM