If you're interested in a Mathey Dearman Single Jackscrew Chain Clamp, a very useful pipe fitting tool, please visit this ebay link.

http://cgi.ebay.com/Mathey-Dearman-Single-JackScew-Chain-Clamp-Model-D-321_W0QQitemZ7570631362QQcategoryZ11774QQssPageNameZWDVWQQrdZ1QQcmdZViewItem