They were offered to folks flying KLM air customers flying in business and Royal class. There is Dutch Genever (35% alcohol) inside them however in countries with strict alcohol restrictions, empty bottles are presented to their customers. These were first offered in 1952. You can read more of their history here.
This is what they look like on the bottom.
And here are their backs. Each one is numbered. Each house is modeled after an actual Dutch building.
No, I have no plans to actually "collect" these, however, should I come across one here or there, naturally I will add to my own little Dutch straat.
I hope you had a good weekend, Everyone!