Battery Details:
5 Hours of battery life.
RCA wireless Mini battery tattoo power supply.
Material: Aluminum alloy and plastic.
Lithium battery: 3 blocks.
Charging time: fast charge, 1-1.5 hours full.
Usable time: normal 8V voltage. voltage stability The status can be used for 3-4 hrs.
Size: 75mm (length) * 32mm (width - thickness) * 55mm (height).
Item Includes = Box, 1x power supply and 1x USB charging cable. 
Instructions for use:
This tattoo power supply machine provides 8 voltages: 5V,6V, 7V, 8V, 9V, 10V,11V,12V.
LCD display 1 means 5 v .and so on.
Press and Hold the O button to turn ON/OFF, click the /- button to adjust voltage.
The Hello battery supply could be working on rotary tattoo machine without cords.
Charging time: 1.5 to 2 hours last working 6 to8hours after full charge.