So, I ordered the part and now get. My intention: 3 Flash Adapter (Sony) to mount it. The production makes a good impression. That is consistent. BUT: the thumbscrews are too short! There are only 3-4 mm in length, then I could use the right. My last attempt will be to find other screws. So I can only awarded 1 star.
Today I have 3 Stainless steel Allen screws M4 12mm retrieved from the hardware store - 0.12 per piece. Behold: so it works fine. It is an indictment that is saved to the 2-3 mm.
Now - according to my application - I can use it and get one star more.