The shortest wireless pen machine of Mast with replaceable batteries. Innovative design, perfectly balanced for comfort, steadiness, and control. Additionally, this machine is practically vibration-free. Battery in the grip: makes the center of gravity lower and the length shorter and more comfortable to use Wireless & Unlimited: two sets of large-capacity replaceable batteries ensure unlimited wireless tattoo work. More powerful brushless motor: Mast new generation brushless motor designed for professional tattoos. Owns stronger power, easy to drive the 4.0mm stroke. Safe Charging: The circuit board is equipped with short circuit, overcharge and over-discharge protection, which is safer Specifications: Weight: 149g Diameter: 33mm Length: 100mm Voltage: 4-12v Stroke Length: 4.0mm Battery Capacity: 1400mAh Motor: Brushless motor Working time: 5-6 hrs, 2A charger can be fully charged in 1.5 hours