I designed this wrench in 2004 after seeing the need. I wanted something better then the traditional pair of pliers to remove the delicate plastic sensor during fuel filter servicing. The wrench is precision machined from T-6061 Aluminum and tolerances are kept to a tight spec to even work on worn or already damaged sensors. Use the handy slot on the other end of the tool to fit the bleeder screw securely and prevent round off. I am convinced that this is the nicest design going since its been imitated many times.