Can anyone provide any guidance to ID this bar stool?  

I tried to post on the identification page, but got no reply..

I got a set of four at an estate sale, and I noticed that they have "Seng Chicago" swivels and that they are dated 1966. Almost any web search for Seng swivels turns up results for Charles Eames furniture. Being that they are post-modern (right?), I am at a loss for figuring out whether they might have any relation to Eames, or if Seng made their own furniture and Eames just used their swivels.. I realize that they are probably production chairs, but any additional knowledge about them would help.

I'd be happy to provide more photos or information. Thank you
<img class="wpforoimg" src=" http://d1t1u890k7d3ys.cloudfront.net/cdn/farfuture/hErEjWNjirWP_JzExHD7Vq