The Irwin Utility Knife Blades features patented Bi-Metal technology that sets new standards of performance. The unbreakable spring steel body delivers superior flexibility to prevent breaking (under normal working conditions). The Irwin 2084100 has a high speed steel cutting edge which stays sharp longer than traditional carbon utility blades. Features: * Features patented Bi-Metal technology that sets new standards of performance * Spring steel body delivers superior flexibility to prevent breaking (*under normal working conditions) * High speed steel cutting edge stays sharp longer than traditional carbon utility blades (*tested on 20lb recycled paper) * Fits most utility knives What"s In The Box: * Irwin 2084100 Bi-Metal Utility Knife Blade 5-Pack