... steel use: steel, cast steel,malleable iron,sintered metal e 1/2 reduced shank drill bit *hot fully ground flute with special ... drill bit *heat treated hign speed steel drill bits with 1/2" shank *complete with below moulded storage case,for easy transportion *specification ... :14,16,18,19,21,22,24,and 25mm 1/2 reduced shank ...