Dual-edged trapezoid safety knife replacement blades help reduce workplace injuries. Made from high quality carbon tool grade steel using OLFA's multistep production process for superior sharpness and blade retention. Dual edged trapezoid safety knife replacement blades are ideal for cutting corrugate, shrink-wrap, plastic strapping, rubber, leather, flashing and more. For use in Retractable Safety Knife (SK-4) and Retractable Auto-Lock Utility Knife (UTC-1).