“Assisted braking” belay devices allow a leader to belay the second directly off of the anchor, and have the device lock up in the event of a fall. This has become the modern standard belay method, provided your anchor is stout. The Black Diamond ATC Guide and Petzl Reverso are the most popular assisted braking devices, but pretty much every major manufacturer has their own flavor.
However, one of the minor headaches of using these devices is that it can be quite tricky to lower your second, especially if they are free hanging on the rope (admittedly an unlikely situation).
(If they are able to slightly unweight the rope, giving you just a few inches of slack for a second or two, you can easily lower your second using the Load Strand Direct, or ”LSD” method, which we cover in this tip here. This is a crafty rope trick every climber should know.)
But, in some unusual situations, your second might have fallen below an overhang, perhaps be injured, or for whatever reason not be able to give you a little bit of slack. In this situation, most of the standard belay devices lock up completely, and unlocking them and lowering your second in a controlled manner, known in some circles as “defeating the plaquette,” usually requires some clever tricks with a sling, Munter hitch, and some other other shenanigans that if done incorrectly, can cause you to drop your climber. Yes, it has happened.
To quote Bruce Lee, “The best fight is the one you never have.” Meaning, if you can avoid even trying to defeat the plaquette, with rope shenanigans that might result in a bad outcome, that’s usually the better approach.
Well, fortunately good design has caught up with belay devices. The DMM Pivot is an innovative device that allows you to easily lower a second, even if the rope is under full load.
The connection point to the anchor is a U-shaped bit of metal on a sort of hinge. This hinge allows the device to rotate. So, to lower your second, you simply clip a small-nosed carabiner, nut tool or redirected sling to the “ear” of the belay device, give it a tiny bit of upward pull, and easily lower your second in a controlled way. (It's still best practice to have a third hand/autoblock friction knot on the brake strand when you do this.)
You can’t do this nearly so easily with the Petzl Reverso or Black Diamond ATC Guide.
Given that the DMM Pivot costs about the same and offers better functionality, to me it’s a great choice if you’re looking to upgrade your belay device.
And like most climbing techniques, it's a better show than to tell. Here's a video that shows how to use the DMM Pivot. Start about 5:30 to see the anchor set up and how the “pivot” release works.