The IRWIN Bi-Metal Utility Knife Blade 20-Pk feature high-speed steel cutting edges that stay sharper up to three times longer than carbon utility blades for long-lasting use and increased durability. Designed with patented bi-metal technology, the blades have sharp edges and flexible bodies. Irwin bi-metal utility knife blades have shatter-proof spring steel bodies as well to prevent them from fracturing when used on projects under normal conditions. Created for multi-purpose use, you may use the Irwin blades for a variety of tasks including cutting drywall, boxes and carpet. The 1.5-inch long and 0.025-inch thick blades with a small blue painted strip fit any Irwin utility knives and also are compatible with most other utility knife brands.