This is a (BS) Nederlandse Binnenlandse Strijdkrachten commemorative badge (Dutch Interior Forces). The BS were the Dutch armed forces , made up of mostly civilian resistance people that helped at the wars end to disarm the German army and arrest them. The BS was largely connected to the resistance.
The badges are of the buttonhole type. All bear on the front capital “B”, the first letter of Prince Bernhard. The back features his autograph.
We managed to obtain a small lot of the badges, All are in good condition. The price is naturally per piece.
A bit on the background of the badge: