This is a budget, pressed steel derailleur, slightly reminiscent of a Huret Svelto, DNB or Suntour New Skitter. By 1972 these were all very old designs to copy, so the Belri was not exactly setting the heather on fire in terms of technology.
I think this gear sold while there was a shortage of derailleurs during the Great American Bike Boom, but disappeared immediately the boom ended. Frank Berto claims ‘they disappeared around 1974’.
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