Turn over the Hypno Liquid Timer and watch the liquid slide down turning the hyono wheels. It takes approximately one to two minutes (depending on room temperature) to completely empty into the lower portion. Great prop to keep on a science table for the children to tip, turn and watch as the liquid drips down. Hypno Timer can also be used for teacher or child stress/relaxation, quiet time toy, refocusing prop, anxiety prop, or a timer. The Hypno Timer is 5 1/2" tall.