The Tread Sled is a product made to protect stairs from getting damaged by the rough plastic on the back of the PackOut. Also, to protect the toolbox itself from getting all damaged, as the plastic tends to get destroyed in hard use. The smooth, replaceable Tread Sleds aid in both these problems.1 pair of TreadSleds Installation Instructions:1. Make sure area is clean of dirt2. Dry fit & make sure there is no damage around the mounting area that needs to be scrapped off.3. Squeeze a liberal amount of 100% Silicone around perimeter of TreadSled (as seen in video below)4. Press TreadSled in place5. Secure in place as shown in video6. Either Clean off excess silicone with mineral spirits, OR trim with a blade after it has set up.- Put it to use!