There is another company that sells swivels similar in design to the Do-It ones. Unfortunately I was infected with a hijack virus so my favorites link was lost. What I do remember is there was a company that made these where they had two cylinder rolling sections. The link was one that someone posted here on TU as a supplier for swivels, etc. but it was a Non-US company. Sorry I couldn't be of more help but I will look around to some more.
Allen