What's a COKIN?

[poker]

Look what I dug up. I found my set of COKIN "A" square filters. They were given to me back in highschool by an old friend. I also found the 52mm adaptor that will only fit my Canon 50mm f/1.8.

I don't remember using it much. I doubt I'll use it with my digital stuff. I'll keep it in case I want to get creative with film....like who knows when.

Does anyone have experience with these?

Link: http://www.cokin.co.uk