Cast iron riser rings. All standard sizes diameters and heights/depths are stock items. H-20 traffic rated when properly installed in a traffic rated manhole ring with reinforced concrete. Uncoated cast gray iron, ASTM A48 CL35B or better, AASHTO M306-10 (M105). Made In USA. LEED® certifications available on request. Please use the Contact Form or call us to request info & submittal sheets. 1-800-258-2278 Toll Free or (972) 263-1360 DFW Local.