The Variable Speed Vortex Mixer comes with a rotary dial for speed & time selection. The Mixer has three operating modes: touch, timed, and continuous modes. A three-way power switch changes mode of operation from ‘touch’ to ‘timed’ or ‘continuous’. The Vortex Mixer is designed for use with interchangeable accessory attachments that can hold test tubes, flasks, beakers, and microtiter plates. The sturdy metallic base and perfect dynamic balancing eliminates any movements and dampens vibrations while mixing.