1. 

   Rob Langdon Well-Known Member

   The back has rusted away and it is 23mm in diameter.
   
   

    

   Rob Langdon, May 12, 2024

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2. 

   daveydempsey Moderator Moderator

   Looks like the end of a shell casing.

    

   daveydempsey, May 12, 2024

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   komokwa, kyratango, johnnycb09 and 4 others like this.
3. 

   Marote Well-Known Member

   Not the same type of button, but seems to read 'Solide Neuheit':
   https://www.ebay.com/itm/325505179273
   

    

   Marote, May 12, 2024

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   Rob Langdon likes this.
4. 

   Rayo56 Well-Known Member

   "the text is German, meaning 'solid innovation'. ".

    

   Rayo56, May 12, 2024

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   Rob Langdon likes this.