Precise  #4-84 TPI, 51 Blade Screwpitch Gage

Blades are of narrow leaf design to permit their use in determining pitch for inside as well as outside screw threads.
Blade sets are contained in a study steel protective case with a locking device at each end to secure the entire set foe storage, or for holding an individual blade in position for use.
Each blade is clearly marked with the proper thread size.