A carabiner hooks to my belt (orange is the new black). The panic clip is used to shorten the length of the leash. Halfway down the leash is a swivel link. Then two lines go down, one for each dog. When the dogs start to weave, the swivel link keeps the lines from tangling. The panic clip is convenient and something I had around (they can be had at any marine store). It makes it easy to let them loose when I can give them some line. It's also easy to snap on with one hand. I used Spectra rope since I had it around (I used to rock climb) but I would have anyway. It's incredibly strong, light and wears well.
Would love to hear everyone's thoughts. The dogs love it and so do I.