Kutir Utility Knife Blades are Stainless Steel. All the blades have 8 Pre-Cut Section that Snap-Off easily so that the blade remains sharp all the time. The electroplated blades are extremely sharp to cut faster and safer boxes, wallpapers, carpets, cardboards, vinyl, backer board and ropes easily. Because of SK2 its very strong that you can push hard to cut strong carpet or boxes. Because of Triple cutting edge technology it so sharp and easy to cut through almost any surface. Use it with cautions as it can cut through anything like a hot knife in butter. Heat treated for strength and induction hardened for longevity up to 75% longer-lasting life. HRC: 63-65.