I think this Union pull-chain design, a very competent copy of a Huret from the 1950s, is the earliest of the Czech derailleurs in this collection. It is clearly a close relative of the Favorit (1st style), but the black finish  on the small parts smacks of immediate post-war shortages of fripperies like chrome for plating. Despite (because of?) this, it is a solid, well constructed, item and the small parts are accurately machined.

Strangely the branding is upside down - unlike the later Favorit version.

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1. •Brand: Union
   

2. •Country: (Czech Republic - Czechoslovakia at the time)
   

3. •Date of introduction: 1952?
   

4. •Date of this example: unknown
   

5. •Model no: unknown
   

6. •Weight: 238g including integrated hanger plate
   

7. •Maximum cog: 24 teeth?
   

8. •Total capacity: 22 teeth?
   

9. •Pulley centre to centre: 46mm
   

10. •Index compatibility: friction
    

11. •Chain width: 1/8”?
    

12. •Logic: low normal
    

13. •Pivots: one sprung pivot
    

14. •Material: steel
    

0393/N