High Speed Steel Jewelers' Setting Burs 3.10-5.40mm These hand-cut, high speed steel burs last longer than standard jeweler's burs. They offer exceptional cutting efficiency and are available in a wide variety of shapes and sizes for cutting most metals. All have 3/32" (2.4mm) shanks and will fit most flexible shaft handpieces. Sizes 12-23; diameters 3.10-5.40mm. Supplied individually.