Sympathetic Resonance Box Set 440 Hz, 1 Pair

The Sympathetic Resonance Box Set 440 Hz by United Scientific pairs two matched 440 Hz tuning forks on 7 x 3.5 x 2 inch wooden resonance boxes with felt feet. Striking one fork sets the other vibrating without contact; an adjustable frequency clip produces audible beats for interference calculations, and a suspended ping pong ball shows the vibration. Physics teachers use it for acoustics and wave-property lessons.