The Petzl Reverso, the Black Diamond ATC Guide, the Trango GiGi, and the Kong Ghost are all examples of these "modern" devices. Belaying at the top of a pitch off these devices makes everything easier, you belay off the anchor which keeps you out of the system , you can belay two people at once, and it's easier to eat, drink and do other activities while using these devices because they don't require quite as much attention as other types of belays.
The downside to autoblocking devices is that it can be difficult to lower people with them. The following video shows three different types of autoblock lowers.
In review, there are three types of lowers demonstrated in the video. Following is a step-by-step breakdown of how to do each of them.
1) Simple Lower by Ratcheting Carabiner
The first type of lower requires that an individual crank a loaded carabiner back and forth. When you do this, it will allow the load to lower slowly. This isn't a very good technique for long lowers.
2) Simple Lower with a Nut Tool
In the second lower, you must take a nut-tool or small carabiner and put it in the hole on the bottom side of the auto-blocking device. Once this is in the hole, you will crank it backwards, "braking" the autoblock hold on the rope.
It is important to keep your brake-hand on the brake-strand of the rope.
3) Complex Lower with a Redirect "Braking" the Autoblock Mode of the Device
This final style of lower requires a few more steps than the preceding. Following is a breakdown of the lower:
- Tie off the backside of the rope with a catastrophe knot.
- Place a carabiner somewhere high in the system, above the autoblocking device.
- Run a cord or a sling through the hole in the bottom of the autoblocking device.
- Thread the cord through the carabiner high in the system and clip or tie it to your belay loop.
- Enchain two locking carabiners on your belay loop.
- Munter the brake strand into the topmost locking carabiner.
- Untie the catastrophe knot
- Lean back on the redirected cord, "braking" the system.
- Lower using the munter hitch on your harness.