Proving that there is a happy middle ground between evolution and intelligent design, the ATC has grown a ring on one side that allows it to be used as an autoblock.
There’s a smaller ring on the other side to hook a cord to for releasing the tension. I have a local bar I frequent for that purpose, but this is a better solution in the sense that it’s built into the device.
I’ve only used it to belay and rappel, and it works smooth – like buttah – for both purposes. I was a late switcher from a figure eight to a tube style device, but the ease of use, capability to handle two ropes and freedom from kinky rope syndrome have won me over for good.