The closed end blocks the last cavity, preventing a wire from being pushed past the housing in a 5-circuit build.
No wire stripping or crimping tool is needed for the IDC step itself, though a hand press or arbor press is typical for seating the cable into the housing. The 26 AWG wire gauge is fixed; the slot geometry does not accept other gauges.
The ramp holds the pair together against cable pull or vibration; it releases by pressing the ramp tab. The right-angle cable exit means the wire bundle runs along the board, not away from it — plan the cable routing path before committing the header position.