I've been working on Harleys for over 5 years and when you are doing a service on them you have to check the drive belt deflection. I would rather use one of these and get the belt precise than using the "feel" method. I've never been good with that and would rather use this to let me know exactly what the deflection is. If working on your own Harley, you should have one of these in your tool box. I'd buy another one if mine ever broke.