All Oster® blades are put through a 12 step process guaranteeing quality and craftsmanship. It starts with a fine-grain carbon steel that is heat treated to create a hard surface for greater wear resistance, leveraging a Rockwell Hardness Rating of 62. Then a patented Cryogen-X™ process takes the blades down to a -300 degrees for a deep freeze, producing a harder, sharper blade which extends the product life. Each blade is then hand lapped for a smooth cut finish. These cryotech clipmaster blades are corrosion resistant and stay cooler for more comfort. Used for standard body clipping this set contains 1 Top Blade and 1 Bottom Blade.