As a technician, I've never had the need for one of these. They're super handy for maybe 10% of cars, the rest they're useless. Perfect example is the GM 3.6 in almost all the FWD applications. The tensioner has a 1/2 inch drive hole with maybe an inch between the frame rail and the tensioner. I ended up grinding down the nose of a cheap 1/2 inch ratchet to fit, and that's all it's good for now. Free.99. Those tensioner tools are too long to get enough leverage without hitting other things.