Ha ha. The higher profile of the brake arm draws more attention to the Duomatic. It is a measure of my high regard for that hub that I think it deserves a higher profile.
The adjusters are indeed chain tensioners. It gives me a positive adjustment for chain tension and alignment of the back wheel. Here's an example:
http://www.jensonusa.com/store/produ...Tensioner.aspx
Cheers,