The SK-9 Self-Retracting Safety Knife with Tape Slitter features OLFA's unique self-retracting mechanism, for maximum safety, plus a handy tape slitter at the opposite end of the handle for added functionality. For safety, the SK-9 offers a spring-activated blade that self-retracts the instant the blade loses contact with a cutting surface. The blade has a cutting depth of .75" (19mm). The knife will accommodate three specially-designed, dual-edge blades, all crafted of high-quality carbon tool steel engineered for maximum sharpness and superior edge retention.