I have seen one of these many many years ago and did my head in than trying to work out what its for, almost like its an aid for tying off something as the plunger pulls out to expose that hole near the flange.
so cant wait to find out what it is for :goldnugget:
was from a very strange afternoon summer rain shower last year chuckles was waiting for a ufo to appear was pretty special either way
here are a few more pics.