You are looking at some 16mm Feinwerkbau steel front sight inserts.
Genuine Feinwerkbau part
Sold individualy
Sizes range from 2.0mm up to 3.2mm and are engraved on each insert
If you try to used them to a different brand like Anschtuz or Gehmann, they may not fit properly. They all use the same basic system, but each have a different measurement.(tabs each side)
Duties and processing fees are now included in the shipping price.
Sales taxes (were applicable) are collected by eBaY