Concrete Covers Home » Concrete Covers Concrete Cover Specifications SIZE TYPE OPENING THICKNESS 32" O.D. Concrete none, 4" PVC, 12"x12", 18"x18", 20" round, 24" round & custom 4", 6" & custom 36" O.D. Concrete none, 4" PVC, 12"x12", 18"x18", 20" round, 24" round & custom 4", 6" & custom
