Rapid Tools RT00044 18mm Serrated Snap-Off Blades, 50-Pack serration pattern make the blade sharper, last longer and cut more evenly through formidable material fit any standard utility knife so you can use them in your favorite knife or in any of the Rapid Tools line of quality utility knives available The only blade you will ever use again, as the difference between the patented serrated blade and an ordinary straight edge is simple a cut above 18 mm size blade Fits all medium size snap knives