Our well rings range from 457mm (18") to 1220mm (48") inside diameter and are manufactured in 300mm (12") incremental heights up to a maximum of 900mm (36"). All sizes are manufactured with a 75mm (3") or an 89mm (3 ½") wall thickness, all with interlocking tongue and groove, except 450mm I.D. (18"). Common uses include risers for catch basins, drywells, and septic tanks. A variety of lids are manufactured for each specific size to accommodate the particular end use.