A replacement for #15 or #30 oil saturated felt, designed for steep slope roofing under asphalt shingles, synthetic shingles, residential metal roofing and cedar shakes, 12 times stronger than #30 felt, meets and exceeds ASTM D226 Types I & II and D4689 Types II & IV, 8 square more per roll compared to #30 felt, easier to install - wider, lighter and more coverage per lap, synthetic construction is impervious to mold, lays flat and does not absorb water and wrinkle, enhanced UV protection, no oil leaching, no hazardous material content, fiber grip slip-resistant walking surface, advanced backside non-slip coating, low temperature flexibility. Roll size of 10 sq or 93 sq-m.