16 tooth Metric Pinion, 48 pitch. Has 1/8th" bore.Steel alloy pinions are not heat treated and should only be used with plastic spur gears. Most commonly used on Kyosho and Tamiya electric cars and trucks. In sizes 12 through 24 teeth. 1/8 inch bore. One 5-40 set screw included. 1/16 inch allen ..