Replacement blade for the 4" and 6" Hamilton Marking Gauges. The blade is made from 1095 Spring Steel, heat and cryo treated to a hardness of Rockwell 62-64.  It features a finger nail grind that is designed to cut across the grain as well as with the grain.  It also helps to keep the fence tight against the work surface providing a very accurate and true reference line.  This is not a replacement blade for the panel gauge.