Oster® A-5 Size 4F Blade Item #: 78919-186 Product Description: The best in the business with innovative heat-reducing technology and legendary, sharp-cutting performance. All of Oster® blades are put through a 12 step process guaranteeing quality and craftsmanship. We start 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. Our 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. *Leaves hair 3/8" - 9.5mm *Acts like a comb as it clips through coat *Use when clipping hard coated Terriers &; Spaniel back patterns *Leaves a nice finish when clipping drop coated breeds *Manufactured in the USA with superior craftsmanship and pride, these blades offer the essential tool for professional results groom after groom.