optibelt TT frequency tension tester is used to check the tension of drive belts

https://www.optibelt.com/en/products/technical-devices/optibelt-tt/ The optibelt TT frequency tension tester is used to check the tension of drive belts by measuring their frequency of vibration. Due to its compact design, it offers universal application possibilities for drives in engineering, in the automotive industry and for many other technical applications. The optibelt TT is designed even for difficult-to-reach places, making it ideal for quickly and easily checking the tension of V-belts, ribbed belts and timing belts.