The Stone hitch (aka Stone knot or Stein knot)

Disclaimer: Rappelling can be dangerous! Especially when using new rope systems! Practice this (and any other new technique) in a controlled environment and with a qualified instructor before you EVER try it in the real world. This video is for entertainment purposes only.
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The Stone hitch is a double strand slipknot that is blocked with a locking carabiner. It's typically used in canyoneering, where rappelling on a single strand of rope is common. The Stone hitch creates two independent fixed strands of rope. It's easy to tie, easy to check, and easy to untie after its been loaded.
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It is CRUCIAL to clip the locking carabiner to BOTH the loop of the slipknot AND one of the two strands of rope between the hitch and the anchor! If you don't do this, the carabiner could pull through the slipknot and the hitch will fail.
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Why use it?
1) Speed up a group rappel. One person can be descending on one strand of rope while at the same time someone else can get rigged and safety checked.
2) Provide a belayed rappel. Someone can rappel on a single strand of rope, and they can be belayed on the other strand.
3) Set a precise length with one strand of the rappel rope. In canyoneering, especially if you're landing in water, it's good to have the rope you're descending match the actual length of the rappel. The Stone hitch lets you do this easily.
4) Pull a big load with a rope and not worry about untying a welded knot.
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