Lens hood - what's this bit for?

A few weeks ago I bought a 3rd party lens hood for my 18-55mm zoom, and I've just found something a bit odd:

[IMG]http://i183.photobucket.com/albums/x21/Kingofthemountains/IMGP1015.jpg[/IMG]

The small bit of black plastic is evidently supposed to do this, it unclips and clips back in rather like a battery cover. Anyone know what this peculiar feature is for? Why would you want to unclip a chunk of your lens hood?

It's so you can spin round a polarising filter (if you've got one fitted), without taking off the hood.

Ahh! That makes sense now, thanks!

Guessing it should be on the underside of the lens then, to avoid weird lighting effects?

'Ere DM, what are you doing with my sofa?

Looks more like a tablecloth to me.

Is that hood silver?

Your sofa! Thank god for that I thought it was our duvet cover!!!

It's definitely a tablecloth, and the lens hood is black rather than silver!

I usually try to photograph smaller items on a white background, but this was a hurried spur of the moment thing. I found the removable bit during a quiet spot at a New Year's Eve party!

Ok, so we have two seat and three seat tablecloths.

But on the plus side at least have you probably been to more fun New Years Eve parties (from the sound of it)

Oh, this one was pretty good. One guest was a duck (of the domesticated variety) which just stood around making contented quacking noises from time to time. We also had fireworks at midnight, one of which exploded at ground level after failing to launch!