Mark Figgewrote a review of Petzl William Locking Carabiner on July 22, 2010
I like the caribiner, large surface for loading with the rope. Works great for belay. Great red annodized stripe to ensure its locked. My only gripe (its a big one) is it is so large and smooth it can rotate when you are belaying someone. I have looked down a few times to see it in a position that would cross load it (SCARY!). Yes this is due to the fact that I allowed a little slack in the rope, but we were top roping. Be really careful if you are lead belaying someone when you are giving them slack for clipping. If anyone wonders, i was using BD ATC-XP with it, but you will probably see the rotating with any delay device-be careful!