The Duro-Last vinyl roof membrane is a proprietary thermoplastic formulation consisting of PVC resins, plasticizers, stabilizers, biocides, flame retardants and U.V. absorbents. A weft-insertion knitted scrim that is laminated between two layers of PVC film gives the membrane its strength and durability. The Duro-Last single-ply membrane is available in white, gray, dark gray, tan, or terra cotta.
​
 See link_