Muntpost was a Dutch company that has issued many medals of Dutch royals, and other commemmorative editions since 1976 (under the name Monumunt). In 1983, the name of the company was changed to Muntpost. The company existed under this name until the end of 2007, when it was sold to Sertons-CDC, a company that is still active.
This particular medal was minted in bronze, silver, and probably gold, although it might only have been plated. Year unknown, but the font was popular in the 1970s and early 1980s.