Themed collection

A lot of 1950s-60s enamel pins; some are:

Oil companies and Fuels: The vintage logos of brands like Caltex, BP, or Shell are always in high demand.
Automotive: The GM (General Motors) pin visible in the center has strong appeal for vintage car enthusiasts.
Beers and Alcohol: Historic brands such as Amstel Bier or Trappist have a very active niche of collectors.
Historic or local food brands: Many of your pins feature brands predominantly Dutch/Northern European from the 1960s (such as JOZO, Honig, Zwan, or Albert Heijn). In that specific market (the Netherlands and Belgium).