The toggle is a relatively new method for rigging a retrievable rope. It is fundamentally different from almost all of the other retrievable rope techniques because when you're done, you release the knot at the top of the rope, and the rope falls down rather than having to pull the rappel rope up through the rappel ring.
To rig with a toggle:
The toggle requires a bit of practice to work correctly. Here are a few pieces of advice to consider:
The biggest advantage of the toggle method is that you don't have to pull your rope up and through the anchor after you're done rappelling. This reduces rope grooves significantly. It also reduces the chance of a stuck rope, especially on very tall rappels that have a lip at the top.
You can combine the toggle with a 2-Ring Retrievable Sling and use the same pull cord for the toggle and the sling.
The toggle is an advanced canyoneering anchor tool that requires knowledge, judgement, and skill to use correctly. As with many other aspects of canyoneering, improper use can lead to serious injury or death. Improper use of the toggle can also result in stuck ropes and stranded canyoneers.