Like any tool, use it before you need it to make sure it works. I found the design of these (and the rest of the Ti keys) to be well done and very accurate. These wrenches are not very long, which is usually good for motorcycle repairs. The ends are also a little thinner than my old Craftsman wrenches so they fit better in tight spaces. I recently used my 8mm wrench to bleed the brake lines when changing the fluid. Given the tight area I had to work in, the smaller wrench made the job that much