Sonic belt tension tester measures the vibration of the belt to assist with correct installation or tuning of toothed and 'V' belts. Suitable for checking the tension on all belt drive engines, including camshaft and auxilliary belts. Ideal for both synchronous and V-belts.Frequency range: 10 - 600Hz. Includes 20 memory/data storage settings; auto power off after 5 mins to preserve battery. Requires 2 x AAA batteries (not included). Easily calibrated by the user using a mobile phone app. Please refer to OEM data for correct tension value.