IVY Classic 11163 Roofer's Knife, specially designed for general purpose cutting with precision honed edges that help extend the cutting life. These blades fits IVY Classic blade 11176 and most other standard roofer blade knives, providing a better performance than other brand utility blades. When one blade dulls, just replace it with a new one. Heavy-duty metal construction. Cuts roofing material and shingles. Retractable blade adjusts to exact position - Included.