HPD twist drills, jobber length 1.premium HSS Co 2.plain shank 3.30 degree helix angle ... drill 4.130 degree point angle premium HSS Co HPD twist drills, jobber length Materials: premium HSS Co30°helix angle for drillTolerance ... stub length-increasing rigidity and suitable for 4D~5D drilling..Premium Cobalt HSS with superior TiN coating-higher speed and feed ...