Cellular core construction. Schedule 40 size drain, waste, and vent. NSF listed, ASTM F-891. Cellular core pipe offers the advantages of lighter weight, lower water noise, easier to cut and saw, higher tensile and impact strength. Same I.D. and O.D. dimensions as solid PVC Schedule 40 DWV pipe. Rated for DWV use only. Due to the fluctuation of the PVC resin costs, Do it Best Corp. reserves the right to bill at the prices prevailing on date of shipment.