Fully retractable knife features a safe, retractable No. 11 blade. Easily change the blade as you would with any X-acto No. 11 blade. The knife is perfect for delicate, precision cutting and trimming of lightweight materials, such as paper, plastic, balsa, thin metal, cloth, and film. The soft, triangle-shaped comfort grip provides extra control. Anti-roll handle keeps the knife from rolling off your worksurface. Retractable knife also offers a metal core construction for durability.