The American Line 66-0422 Heavy Duty 2-Notch Utility Knife Blades are made with premium steel using a proprietary grinding process for the best balance of sharpness and durability. They are versatile and multi-purpose, and able to cut a variety of materials including cardboard, leather, linoleum, carpet, rope, PEX tubing, soft metal, etc. These blades are compatible with most standard utility knives such as folding utility knives, fixed utility knives, and retractable utility knives.