APOC Tuff-Grip™ 15 is a UV-stabilized polypropylene underlayment designed to shed water. It provides a secondary layer of protection against wind, moisture, and other elements and replaces the use of #15 and #30 organic roofing felt under asphalt shingles, residential metal and cedar shake roofing materials. Tuff-Grip™ Coating Technology: Securely grips to the roof deck before fastener application, ensuring easier and safer installation. High-Traction Surface delivers outstanding walkability, even on steep, wet or slick surfaces. All-Temperature, All-Weather Performance from -40°F to 240°F.