In reply to lots of posters:
Just because a device isn't what you want, doesn't mean it's pointless. Just because we (the british), myself included, are obsessed by double ropes, doesn't mean the rest of the world are.
For £13, you can have a great device for single pitch sport cragging. Sounds pretty good to me!
Tom, old ATC's are scary to ab on, if you've got thin ropes, a big sac and are a tubber like me. Well, I bricked myself one too many times, even using 2 krabs, so invested in a guide which is loads better.