Like so much about the SCW, this is an elusive item, but supposedly it was to be given by the Republic to every IB man before he left Spain.
A Brit combatant whose name i've fogotten wrote a book in which he discusses the medallion.
The design, which appears on much of the literature from the VALB, consists of a raised fist on a map of Spain, a star & motto.
If anyone can help i'd like to get a close-up jpeg of the actual medal, & also of the 50th Anniv. medal (which should be easier to find!)
As far as i know the original IB brass medal has never been photographed. It's also not known how many IB men actually received it.