Outdoor Edge RR50-6 RazorSafe(TM) System 5" Boning/Fillet Replacement Blades (6 Pack)Set of six Japanese 420J2 stainless steel replacement razor-blades. Each blade is precisely heat treated and hand finished to a surgically-sharp cutting edge.PLEASE NOTE: These 5.0" blades fit all 3.5" FOLDING AND FIXED BLADE RazorSafe(TM) System knives. When used in a FOLDER the 5.0" blade cannot be closed and should be removed immediately after use and stored safely in the enclosed BLADE BOX.Specifications:Steel: Japanese 420J2 Rockwell-C hardness: 57Blade: 5.0 in / 8,9 cm