I'm trying to add an element of idiot proofing to my projects so that i don't accidentally connect up single (or double) row Dupont style connectors the wrong way round. Many moons ago you could get a thin plastic insert that was used to block an unused pin on the female connector that theoretically stopped you from mating the male and female halves the wrong way round.
I'm looking for some of those plastic inserts now but can't seem to use the correct search term in google. I've tried the word "Dupont" with words such as polarising (or polarizing), keying, blocking etc, but without much success.
Does anybody know the correct terminology for those plastic pins?