OLFA 9048 SK-4 Self-Retracting Safety Knife. Safety experts rely on OLFA� cutting tools like this Self-Retracting Safety Knife because OLFA� Safety Knives provide an enhanced level of protection. The knife features a textured, slip-resistant handle that increases grip and control for safer use. A gently curved blade slider and spring blade that automatically retracts add to the knife's safety. Use this knife for cutting light to heavy-duty materials such as cardboard, packaging, film, trimmings, shrink wrap and strapping. Good For: Use in commercial, industrial, retail and distribution facilities. Cuts corrugated and packaging materials, shrink wrap, plastic, film, strapping and more.