OLFA UltraSharp black 9mm snap off knife blades for cutting jobs that require superior sharpness and maximum performance. These high-quality, carbon tool steel blades are specially double-honed for extreme sharpness and are 25% sharper than OLFA silver 9mm AB blades. Ideal for industrial applications and construction materials including drywall, linoleum, carpet, flooring, insulation, and roofing materials. OLFA #9148 fits all OLFA 9mm utility knives. 13 cutting edges per blade. PACK OF 10 blades.