This flat top fine tuner knob with a 6/32 thread is for the Flyer tremolo system or the 2500/20 Traditional fulcrum models. There were two types of knobs used for the Traditional models. Flat (6/32) or Dome (6/40) top. Inspect your bridge to see which one you have. This is the flat top version and other one is the 8385 dome fine tuner.