Just one small nick on a pinion can eventually destroy a plastic spur gear! With that in mind, RPM designed this case that holds each pinion on its own post and the lid snaps shut, so there is no need to tighten the set-screw to hold the pinions in place! Included with the case is a peel-off decal sheet with two pinion to spur gear ratio charts for both 48- and 64-pitch gears. The appropriate chart can be placed in the recessed area on the bottom of the case. Also on the decal sheet is a set of numbered squares from 14 to 31 (gear teeth), that can be adhered to the inside of the case. There are ten blank squares so you can write in your own numbers if needed. Available in black or translucent blue.