Black blade ideal for applications requiring extra-sharpness. The OLFA UltraSharp black heavy-duty snap-off blades are exclusively designed for maximum cutting performance and are ideal for applications where superior sharpness is required. Made from a high-quality Japanese grade carbon tool steel, the OLFA black blades are double-honed for extreme sharpness and are 25% sharper than the OLFA silver Heavy-Duty LB blades. Long lasting, durable snap-off blade - a new sharp edge with just a snap. Blade container locks for safety. Fits most Heavy-Duty handles. 8 cutting edges per blade. 50 blades per pack. Olfa North America.