i don' know either.. but looks similar to ones used on the hirondelle retro-direct bicycles except those don't have the chain-keeper bits:..
http://www.m-gineering.nl/
Andrei Padlowski Glen Ridge, NJ
On 4/6/07, Ray Homiski <classicbicycle@gmail.com> wrote:
> Ran across this part on ebay and have never seen it before. Not even sure
> what it is nor how it would work. Perhaps it is just a chain tensioner for a
> tandem but I am not sure at all what we have here.
>
> http://ebay.com/
>
> I am just plain curious.
>
> Ray Homiski
> Elizabeth, NJ http://ebay.com/