The OLFA SK-4 Semi-Automatic Self-Retracting Safety Knife is ideal for those looking for precision cutting with superior safety features. The blade is spring-activated and retracts when lifted from the cutting surface, minimizing accidents and unwanted cuts. The powerful stainless-steel spring ensures blade tension on every cut. The SK-4 Semi-Automatic Self-Retracting Safety Knife comes preloaded with an exclusive Dual-Edge Safety Blade for unmatched sharpness and edge retention. A simple flip of the blade allows for both right-handed and left-handed users. Blade changes are fast and tool-free.