The NMTB tool shanks had the 7 in 24 taper, but they also had a constant diameter tail (pilot) at the end of the shank that was described in the 1927 patent. Subsequent design variations dropped the tail (making the shank shorter) and put a V-groove in the flange that aided automated tool changing. Modern designs started using power drawbars that gripped pull studs (also known as retention knobs) that were screwed into the tool shank rather than screw-in drawbars. The power drawbar would grip the pull stud rather than screwing into the tool shank.