LARGE CAPACITY: compatible with all standard RCA rotary tattoo machines. 1300mAH lithium battery, with fully charged, it will last 3-6 hours depending on personal usage and the tattoo machine. VOLTAGE ADJUSTABLE: Voltage 6 7 8 9 11V adjustable. suit your different needs, such as miroclading brow, henna tattoo, lining and shading. The last used voltage is automatically restored after power-on. SAFE: Tuffking Tattoo battery with output short circuit protection and overcharge/overdischarge protection. EASY TO CARRY: Tuffking tattoo power supply is made of aluminum alloy, small size, light weight. convenience to carry with for tattoo artist. WHAT YOU GET: Tuffking wireless power supply, USB charging cable, guide manual, our worry-free 60days warranty, and friendly customer service.