2-Notch Super Hook Blades – 100 Pack Primegrip blades can be used with most utility and roofing knives to cut roofing shingles, felt paper, foam board, insulation, shingles and other building materials. Manufactured from high-grade carbon steel and induction hardened for longevity, our blades last up to 75% longer. • Can be used with all Primegrip knives • Induction-hardened edge offers 75% longer-lasting blade life • Heat treated for strength and induction hardened for longevity • Available in 5-Pack or 100-Pack