This patio decking riser block is an accessory that allows you to add 3" of height to a pier. If the ground is not level, riser blocks are used to level the decking system. They can also be used on a level surface to heighten your deck for a more dramatic, taller look. The riser blocks fit perfectly over the piers and remain secure when anchored into the ground. Risers must be placed under the pier before assembly. This is a 2 pack of 3" Risers.