Page 92 - Jane Renolds - Knots Your Complete Step by Step Guide to Knot, Knot Uses, and Knot Tying

Radium Release Hitch

When you encounter technical or mechanical issues, you can use this knot
to help you transfer load back to the main line, and to make sure that belay
line would get some stoppage.

http://www.animatedknots.com/imagesprelim/radium_release_hitch.jpg
Instructions:

1. First, make a Figure 8 Loop and make sure to have it hooked to the
end of the carabiner.
2. Let a loop pass through the carabiner, and then under the lower one.
3. Now, make a super munter hitch near the top of the carabiner.

4. Tie a half hitch and end the knot with an overhand knot.