SHARK M Machine tap, HSS-E-PM, through holes, M3-M20, Green ring The DORMER E471 is a SHARK (green ring) machine tap with skin bevel for through holes in aluminum, brass and bronze. Made of HSS-E-PM material, clear uncoated version. The maximum thread depth 2.5xD. Broach form B (3.5-5 courses). Also available with SuperB coating for even higher performance (E472). Replacement of E358 SHARK-line, recognizable by the colored ring on the shaft that indicates which materials it is suitable for, is the top line within the Dormer machine tap range. Has many loyal users due to the high reliability and productivity.