Oster CryogenX Blade, Size 40 are produced from the finest high-carbon steel and handcrafted to our rigorous standards, providing unparalleled precision and performance. Furthermore, Osters U.S. made blades are hardened to RC62-66 (Rockwell Scale C) in-house prior to receiving a cryogenic treatment which further enhances the hardening process. Fits OsterA6, Golden A5, Turbo A5, Power Max and