The Kuat 1-1/4" to 2" adapter is a device that allows you to attach a bike rack or other accessory with a 1-1/4" hitch to a vehicle with a 2" hitch receiver. It is made of aluminum to resist corrosion. The adapter is fitted to the side of the 1-1/4" shaft to fill the 2" opening of the vehicle's hitch receiver. It has built-in locking mechanism to secure the adapter in place. It can also be useful if you have multiple vehicles with different hitch sizes and want to use the same bike rack or accessory on all of them.