Retaining wall block are designed to be laid without mortar and often require no masonry footer. This lends them to be laid by non-professional as well the pros. We manufacture 5 sizes of retaining wall, suitable for tree rings on up to commercial earth retention. The smallest ( Nursery Stone) and the largest (Concord Block) are solid units. The other 3 products use hollow wedge shape units, with a pin retaining system, and a solid cap unit. From small to large are Nursery Stone 4" high, 6" Stonewall, 8" Stonewall, 8" Gravity Stone and 6" Concord Wall. The two different height Stonewall products besides retaining wall application, make fire pits & wishing wells.