Olfa SK-4 Retractable Safety Cutter Revolutionary spring-retractable safety cutter features right or left handed operation, powerful return spring, stainless steel blade channel and ergonomic grip. Eliminates injuries because blade remains extended while cutting and automatically retracts the instant the blade loses contact with the cutting surface. Use this knife for cutting light to heavy-duty materials such as cardboard, packaging, film, trimmings, shrink wrap and strapping. (Olfa SK-4 #9048)