A paver base is made up of three levels: subgrade, subbase, and base. These layers are composed of various materials with different support roles. The compacted earth beneath the installation site makes up the subgrade, which is the lowest level. A subbase is the middle layer of support that is placed on top of the subgrade soil. Pavers made of the highest material are set up on a base. https://modutile.com/product/gravel-pavers-outdoor-basketball-court-base-24x24/