Petzl Pirana

Con: Can only be used with certain carabiners.

Pro: Because of snug carabiner fit, it is almost impossible for the 'biner to flip and become side-loaded.

I got one of these to keep in my tree climbing gear bag. I wish I could use it for rescue, but it doesn't have the NFPA's stamp of approval (yet). As with all gear, practice in a safe environment with this device before using it in the "real" world.

This is NOT just another figure 8 descending device. It is a multi-friction device originally designed for caving, but has found favor in almost any sport or profession that utilizes rope.

The best feature of this device is that friction can be added or subtracted while the device is in use. This is accomplished by wrapping the rope around various horns and/or bars. Additionally, there are 3 ways to rig the Piranha to match the weight of the user, size of rope, or compensate for extra weight such as a heavy pack or even another person during a rescue operation. For safety, it can be rigged without removing it from the harness - None of these things can be accomplished with with an ATC or an "8".