This is a 10 Gulden 1875 Netherlands gilt cardboard pattern. It is the only one in existence! It is certified by PCGS as SP63 Gilt Cardboard Pattern!
Most cardboard trials are struck on just one side, but this one is made like an actual coin, double-sided with a raised edge and then gilded making it appear like a gold 10 Gulden 1875. It is one of the rarest patterns from the Netherlands.
It is amazing that this cardboard pattern has survived over a century! It is considered unique.
Here is an original display from the Bank of the coins
and cardboard that were tested by the Mint.
For comparison, here is an 1875 10 Gulden struck in lead from the Dutch Bank.