For demonstrating the production of beat frequencies. Comprises two nickel plated forks A (440 Hz) mounted on individual wooden boxes. One fork is provided with adjustable mass by means of which frequency may be shifted from the nominal 440 Hz. When both forks are sounded a clearly audible 'beat' is produced its rate depending upon the difference in frequency between the forks.Used to hear dissonanceOne fork is adjustableComes with mallet and bases Note: These are designed for physics experiments to create beats and are often not exactly 440Hz (usually 436-444Hz). They can be adjusted to create beats within each other or to match each other.