I think that this is an early Falcon SS derailleur, branded up for Columbia. It is slightly interesting in that it is an early example of an American manufacturer branding up a Taiwanese derailleur, rather than a Japanese or European model (like Schwinn or Raleigh).
It’s plenty rusty.
- Derailleur brands: Columbia, manufactured by Falcon
- Country: USA, manufactured in Taiwan
- Date of introduction: 1980?
- Date of this example: unknown
- Model no.: unknown (hanger plate stamped ‘A04’)
- Weight: 301g including hanger plate
- Maximum cog: 28 teeth?
- Total capacity: 28 teeth?
- Pulley centre to centre: 54mm
- Index compatibility: friction
- Chain width: 3/32”
- Logic: top normal
- B pivot: two sprung pivots
- Materials: steel