Disposable Carbon Steel Surgical Blades, Sklar, #20. Sklar's Disposable, Sterile, Carbon Steel Surgical Blade #20 is a larger version on the #10 Scalpel Blade. It has a curved cutting edge and a flat, unsharpened back edge. The #20 Scalpel Blade is typically not used in surgery, but may be if a long incision or digit amputation is necessary. Disposable blades are available in bulk quantities of 100 per box.