Product is used for generating waves with a string or for use with a ripple tank Overall height: 5.5 in Overall diameter: 4.5in Plastic item with foam inside For use with square wave generator The amplitude is +/- 3mm The vibration generator is a sturdy, user-friendly tool for providing electronically controlled waves - this allows one to create ripples for the study of wave motion. (Recommended for use with a square wave generator)