The power supply controls the voltage flowing to your tattoo machine. There is no single ‘correct’ voltage at which you should run your tattoo machine since the appropriate voltage depends on the style and specs of your tattoo machine, the style of the tattoo, your preferences as an artist, and the location on the body being tattooed. Generally speaking, lining and bold tattoo styles will want higher voltages (~5.5V and up), while shading, blending, and softer tattoo styles will want lower voltages. All tattoo power supplies offer some range of voltage adjustments. Most tattoo power supplies use clip cords or RCA cables to transfer power between the power supply and the tattoo machine. Most also provide the ability to connect power supply accessories like a footswitch, allowing you to turn your tattoo machine off and on while keeping both hands available.