You still have to use a feeler gauge , but instead of using an Allen wrench to adjust it and feel for how tight it is , the tool has a spring in the middle of it that ' s designed to bend to a 90 degree angle when you have the right amount of tension . Takes a bit of the guess work out of it . I want to get one because I always second guess if i got it right when I ' m done with a valve adjustment . <| sep |> Because they developed a system where 3 digit road numbers starting with an even digit serve one purpose , odd number ones serve a different purpose , and the two digit roadways are the main routes . Your system makes less sense from a simplicity standpoint because both 494 and 694 have northbound and southbound stretches .