Local Craigslist ad. http://denver.craigslist.org/for/4254082852.html

Guy must have been given these or he is a doofus:

30 MM Rifle Scope Clamps
Used to hold the Scope to the Piccadilly rail.
Yes, as you can guess, he's selling a set of rings.

Obviously for a British rifle, as they are for the Piccadilly Rail.
I believe that is the train that goes by Piccadilly Circus, in London, isn't it ???