This knot is use to tie two ropes of the diffrent diameter together. This knot is stronger than the Sheet Bend knot
Make a bright in the larger of two ropes to be joined.
Tuck the second line and tuck it up through the bight
Bring the end around and beneath the bight in the other rope.
Tuck the working end beneath itself so both short ends are located on the same side of the knot.
Bring the working end around and beneath the bight and its own standing line once again, keeping it to the right of the original pass.
After that tighten the knot and you're done :D good luck trying