NT professional black snap-off blades with extra sharpness for standard duty utility knives.These specialty blades are packed in protective plastic container with a convenient hanging hole.These professional blades are made of high quality carbon tool steel and produced through multiple stages of precise process to obtain the ultimate sharpness and optimum edge-retention.With even more vigorous steps taken during the finishing process, the cutting edge of these black blades have even finer sharpness.Recommended for professional use only due to its fine delicate edge.50 carbon steel blades per pack.Good for craft & hobby projects, professional artists or installers.Made in Japan.