Hi
There are Umarex markings on the gun, you can see it on the 5th picture.
The Flash Hider does screw off.
I also think there should be a short Magazine with it for the 'k' version.
It does seem to be the same size as the original so upgrades should fit. I think the owner of the gun is looking into it. I shall update the thread if & when he does.
I know the shop that got these had limited supplies. PM me if you would like to know the shop.
Regards
Paddy.