The Touch Vortexer can mix the contents of tubes up to 38 mm in diameter. The unit may be set to run continuously or to activate when any tube is touched to the cup. Designed with a permanent-magnet, filtered DC motor, the Touch Vortexer will run cooler with less motor stress. The variable-speed motor produces constant power and is less susceptible to overloading when excess pressure is applied. For 110V, 60 Hz. (PV6)