Outdoor Edge RazorSafe 5in 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. SPECS Steel: Japanese 420J2 Rockwell-C hardness: 57 Blade: 5.0 in / 12.7 cm