The Spear and Jackson CMTG Mortice Gauge is designed to mark a line parallel to a straight edge The Spear & Jackson CMTG is a hardwood stock and beam with brass wear plates and locking screw designed to mark a line parallel to a straight edge. It is extremely long-lasting and durable. Features: Internal Brass Thread Hardwood Stock and Beam Brass Wear Plates and Locking Screw Specification: Mortice Gauge: 8" Brass Plates in Block: 7 x 3mm Brass Bar in Block: 12mm diameter