BLACK RING machine tap, DIN 371, HSS-E, M 4 x 0,7 

cast iron GG, spheroidal graphite iron GGG - MagnesiuAlloys - for through and blind holes surface treatment nitrided: - increased surface hardness - high abrasion resistance - improved anti-friction properties Thread type: metric ISO-thread DIN 13 Norm: DIN 371 Material: HSS-E