straight grooves, HSS-E, metric ISO-thread, right thread, Tolerance field ISO2 / 6H, forme of taper lead B (3.5-5.5 x P), cylinder shank with square piece, number of teeth 2 Power class N For short- and medium-chipping materials with a tensile strength of Rm > 350...1000 N/mm2. Length of taper lead: 4 x P Hole Type: through holes. Designs: M1...M2.2: N320-3, reinforced shaft, DIN 371