Wheel for M12 Threaded Rod

This is a 54 tooth pinion wheel for using an M12 threaded rod in a rack and pinion component. It has a 3/8" hole for the shaft, and a slot for a shaft 10x8x3mm shaft key.

The weird combination of measurements is based on what was avaliable and cheap at my local hardware store (in this case M12 rod, 3/8" axle, and 10x3mm alumimum extrude).