For use with A5 and PowerPro Clippers. These blades are coated with titanium carbonitride for 3 times longer blade life and smoother cutting. Cutting edge has Rockwell hardness (HRC) of over 80 but are not brittle. The coating will not flake off like regular chrome can. Significantly longer wear life. The Oster Elite Cryogen-X Size 40 blade leaves hair 1/100. The Size 40 blade should only be used by experienced groomers. An ideal blade for show poodles. This blade is the blade of choice among veterinarians for prepping pets off all types for surgery. Cryogenics: Increased blade durability. Blades stay sharp longer. Less sharpening required. Made in USA.