There was a Belgian company "invented" a "new type" of grenade launcher back in the '70s and this could be it.
The "invention" just happened to be a copy of the COSTEN Grenade Discharger Cup which was mass-produced for the British Army in World War I and used with the Number 5, Number 6, Number 23, Number 36 and Number 36M Mills Bombs.
This is just the same; notice the adjustable gas bleed ring at the base of the cup; that's how you adjust the range on the thing.
Nuthin' new under the Sun.
Those who do not know history are condemned to repeat it. On the other hand, those who do know history sometimes can make a fortune by stealing from it and not giving credit where it is due.