The JJF 1216-2009 standard applies to the calibrating of sonic belt tension meters, which are used for the measurement of the static tension of drive belts. The sonic tension meter calculates the belt tension by measuring the inherent Frequency of vibration of the belt after being subjected to Impact under static tension. The standard refers to the Measurement specifications of the relevant acoustic and force measuring instruments to ensure the accuracy and conformity of the instrument. The sonic tension meter consists of a microphone, Frequency measurement unit, Control Unit, display unit and calculation software. It is equipped with a bendable extension rod for easy operation. This specification ensures the Reliability and Measurement accuracy of the sonic tension meter in practical applications.