In reply to comedy_phil:
Thanks for your comments, I have located one and found it a dream to use.
Just for the haters, It is brilliant for thin ropes and light climbers. Lucky for me this is its intended use. It is so much easier to load than a Gri Gri and locks perfectly.
Another good alternative is a Cinch by Trango, or just a good old fashioned sticht plate!
Happy climbing