X-Acto - X-Caliber Retractable Utility Knife - Carded - X-Acto X-Caliber Retractable Utility Knife is great for delicate cutting and trimming of paper, film, and acetate. Push-button retractable stainless steel blade and pocket clip. Includes one X-Calibre Retractable Knife Blade. Xacto X-Calibre RT is a 4-7/8 inch anodized aluminum pen-type utility knife with push-button control of a retractable stainless steel blade. Perfect hobby knife for home, school, studio, shop. Uses No. 95 X-Calibre refill blades.