Since I've been tossing around the idea to install a damper control for variable air supply, I figure this may be a good topic to explore. Here's a link on one for sale on eBay, the price seems reasonable, and there are plenty in stock. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=330199862056&ssPageName=ADME:B:WNA:US:1123