Ignacio Rwrote a review of Black Diamond ATC Guide on July 25, 2009
It has all features available, it's easy to use, cheaper than petzl(what isn't). Great for the gym, sport or trad. Medium and high friction modes, autolocking, you can use a cordelette or a carabinner to help you release the brake. You can belay two climbers on single ropes or one with half/twin ropes on virtually any useable rope diameter. You can rappel off the medium friction side, with a trickier setup you can also rappel with autolock.