Features:High quality physical experimental instrument, durable and practical.Two tuning forks of the same efficiency are made of the whole 45# carbon steel.The edges and corners are neat and the surface is chrome plated, the frequency is 440 cycles per second.The tuning fork set is used to demonstrate the resonance of sound in school.Can be used as a general tuning fork of a variety of experiments, such as the sound of the occurrence, interference, sound conduction of various substances.Specification:Condition: 100% brand newFrequency: 440 cycles per secondFork section size: 6.5 * 16mm / 0.3 * 0.6inTuning fork arm length: approx. 109mm / 4.3inDistance between arms:17mm / 0.7inPackage List:2* Tuning Fork2* Wood Resonator Box1* KnockerNote:1. The tuning fork should be protected from breaking and high heat to prevent frequency change.2. The tuning fork and the sound box should have a reliable connection and should not be shaken when the tuning fork is inserted or removed.