This is a professional quality Dual Digital power supply set. The supply box can be used for dual machines with both machines attached at the same time. Allows tattoo artists to connect both liner and shader machines at the same time (requires 2 clip cords.) Just flip the machine switch on the lower left hand corner to switch power from liner to shader. The digital ultra bright LED screen makes this power supply much easier to read as well as giving it a much more accurate readout. Include a 13 dial potentiality with 110/220v conversion switch in back. Durable metal chassis frame, not like other fragile plastic models. Top of the line Regulated tattoo power supply. The fully digital display shows you everything you need to know on one screen.