32 pitch alloy pinions are not heat treated and should only be used with plastic spur gears. If you only run plastic spur gears these pinions are the perfect choice. In sizes 9 through 22 teeth. 1/8 inch bore. One 5-40 set screw included. 1/16 inch allen wrench (NOT INCLUDED) fits the 5/40 set screw. 32 pitch Alloy Pinions are not marked with tooth number.