The Supjam Mundial is an interesting derailleur. It is extremely derivative of the Simplex Tour de France - with one absolutely crucial difference - the pulley cage pivot is between the pulleys and offset from their centre line. The Simplex Tour de France has the pulley cage pivot concentric with the guide pulley. It is not impossible that Supjam's modification gives a greatly improved change - but it is still odd, because Lucien Juy, the owner and chief designer at Simplex, was adamant that his way was the only correct one. Why did Supjam copy something so faithfully - if they were then going to commit an unpardonable heresy?
The b-pivot bolt is labelled 'M-U-57', very much in the way that Simplex labelled the 1951 Simplex Juy-51 with 'Simplex JUY 51' on this bolt. You might guess from this that the Supjam Mondial dates from 1957.
This example is a Mundial Especial, with high gloss, lushly chromed steel parts. It also has a chromed, steel, outer pulley cage plate stamped with 'Especiale'. Finally it has one pulley bolt labelled '3 Velocidades' - so it is a 3 speed.