This rubber disk acts as a pad that fits into the base of the PVC Adjustable Pedestal system and is sloped 2 degrees. Up to 3 disks can be stacked to compensate for up to 6 degrees of slope in the subfloor. When installing a raised deck over a sloped subfloor, theses disks allow th PVC adjustable pedestal to sit perfectly vertical. Disks are commonly used with the PVC Adjustable Pedestal system to compensate for the subtle slope designed into flat roofs to accommodate for drainage.