Permatite natural open-cell rubber, combined with a non-stretch backing and an aggressive rubber based adhesive. Dortite sponges are constructed of natural open-cell sponge rubber, combined with a non-stretch backing and a very aggressive rubber-based adhesive. Applications: used in HVAC, commercial roof traps to minimize vibration, and off-highway equipment door seals. Ideal for weather stripping, sound and vibration dampening, cushioning, dust proofing and insulation. Meets ASTM 1056-68 RO12. Non-stretch. Easy-to-use versatility. Excellent memory to retain shape. Long product life. Use for weather stripping, sound vibration dampening, cushioning, dust proofing and insulating. Polymer: natural rubber. Compression/Deflection: 5 - 10 psi medium. Density (P.C.F.) average: 26. Temperature range: -20 degree to 200 degree F [-28 degree to 93 degree C]. Method: trim to size; remove release liner; apply to a clean dry surface. Preparation: surface should be dry, clean from oils and debris. Temperature: moderate conditions. Shelf life: 1 year. Air-tight plastic covering. Adhesive surface. Fabric base. Black color. Measures 25-feet length by 1-inches width by 7/16-inches height.