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 a twist of the grip. This Mast Lancer machine has two replaceable wireless batteries, charged fully in 2 to 3 hours.