Of course we know What does YKK mean on zippers?
Damn, I wish I hadn’t. :rolleyes:
So I googled for YKK.
http://www.ykkeurope.com/products/zippers3.php Aha, that pull thingy is called pull tab or puller.
http://www.howstuffworks.com/zipper.htm tells how zippers work and gives links to their history. Nice to know, but nothing about holes.
I could imagine the flesh of your fingers is meant to bulge into the hole, improving the grip. Makes no sense for holes as small as of Model G in this image. Is the dent (models F+G) at the outer end of the puller the point where you really get hold, and the hole just allows to reach around it? Not all zippers have that dent. Has it to do with Zipper lock? If they are made to fit human fingers, why varying hole sizes?
Have I no sense of design? Even if you restrict yourself to punching them out of flat ribbon steel, bending the pullers in a wavy shape would give a much better grip area.
Why a hole? Does it copy the look of old zippers with heavy iron rings? To put a padlock through? Metal saving? Something to tie a price tag to?