This kit is for updating your existing Hobby Grade Mecanum Wheels to Competition Grade Mecanum Wheels.

Parts are included for upgrading a full set of four wheels.

To install the new threaded roller pins:
-Remove the rubber rollers from the existing steel pins and drill a small hole in the end of each roller for the 2-56 screw to fit through. A 3/32" drill bit can be used, or something similar in size.
-Insert the new threaded pin into the hub, press the rollers on, and tighten the 2-56 screws (using the included 0.050" hex wrench) until the rubber begins to deform. Loctite on these screws will keep the rollers in place.

The price is simply the difference between the Hobby Grade and Competition Grade sets. You get to keep the plastic hubs and steel pins (good for use on other bots!) but you must drill holes in the rubber rollers yourself.