Blade for Challenge 30 1/2 305X paper cutters, standard inlaid carbon steel (AKI-I) by Alliance Knife Company. This blade measures 35.75" long x 4.000" high and .375" thick, with 12 holes. (Challenge I.D. is 47507.) When ordering knives, please double-check the brand, model and serial number of your cutter, and measure your knife carefully. Also available in high speed steel.