Oster Cryogen-X blades are made using a 12 step process that ensures superior quality and craftsmanship. Oster’s patented Cryogen-X process take the blades down to -300o F producing a harder blade and then hand lapped for a smooth cut finish. The size 40 blade leaves the coat 1/100" and is a great blade to use when using a guide comb for longer lengths. The size 10 blade leaves the coat 1/16" and is also a great choice when using guide combs for longer lengths.