This high quality 4th wheel kit fits 2012 and newer Arctic Cat Pro chassis models. This kit DOES NOT fit the Sno Pro 500 & 600 race sleds. This 4th Wheel Kit will take 50% of the load from the two inner rear wheels. It is a known fact that there are problems with the stock inner rear wheels. If there is a wheel failure with either of the stock wheels, your sled will no longer be rideable. With this wheel kit in place, you can continue to ride. Another benefit is that it keeps full support across the entire width of the track to prevent catwalking (veers left or right under hard acceleration). One more benefit after installing the wheel kit is that it is easy to check track alignment just by looking at the distance between the edge of track and the outer wheels. The distance should be the same on both sides, if not adjust accordingly. The wheel kit also gives your sled a complete look with rear outside wheels. This kit uses stock Arctic Cat wheels and is available with or without wheels.