This sonic belt tension tester is designed to check the tension on all types of drive belts including camshaft and auxiliary. The meter measures the vibration by using the microphone to convert the tension level when installing a new belt or making adjustments. The tester comes with a flexible probe, ideal for restricted engine bays. There are 20 internal memory data storage slots and the device automatically powers off after five minutes of inactivity to help conserve the battery. Requires 2 x AAA batteries (available separately).