Mast Lancer wireless tattoo machine can work 8-12 hours with one battery for tattooing,has LED screen shows operating voltage and 0.1v voltage adjustments, battery capacity is 1900mAh. Anodized aircraft aluminum body. Lightweight and precision machined. Features jumpstart and memory functions. Stroke Length: 3.5mm.? Adjustable cartridge needle length from 0mm up to 4mm with twist of the grip. This Mast Lancer machine has two replaceable wireless batteries, charged fully in 2 to 3 hours. If the one you choose is out of stock. We will ship the other colors random. Specifications: Machine Weight: 158g Battery Weight: 34g Length: 129mm Diameter: 30mm Stroke Length: 3.5mm Motor Speed: 10V/10500 Rpm Battery Capacity: 1800mAh