Vinyl siding that has been certified to meet or exceed the ASTM D3679 standard through VSI's program has passed all the requirements of ASTM D3679 , as verified by an independent inspection process, including unannounced plant visits twice each year. Vinyl siding products can also be certified for color retention in accordance with ASTM D6864 or D7251 through VSI's program. The official list of VSI certified products and colors is updated frequently to provide the most complete and current listing. Click here to view a list of VSI certified products and colors or look for VSI's Vinyl Siding Product Certification Program label when you purchase siding.