Swiss Tech Utility 18mm Blades package of 5， heavy duty SK5 steel utility blades stays sharper, longer life than standard carbon blades. Swiss Tech 18mm Blades - 5 Pack are engineered to fit Swiss Tech and most standard utility knives. The blades are an excellent accessory to have in your toolbox or utility drawer. These heavy-duty blades are perfect for a large variety of applications and can be used in a myriad of projects. Whether you are opening up a package or cutting up some linoleum to get the fitment just right, these blades are exactly what you need to get the job done. These Utility Knife Blades are of a standard size and fit within any standard utility knife. The blades are manufactured with a sharp edge and designed to maintain that edge as you are cutting through various materials whether it be linoleum, carpeting, cardboard or even tar paper.