The screws just reached me today.
Thanks to Deans Marine from Peterborough , which are the dealers of Raboesch - the screws maker.
Normaly people use them for RC models , but the 20 mm 3 blade model is just perfect for my U-552.
If You ordering some for Your project remember to order left and right.
I need to fix it to my drill and sand them to the point - not big deal.
TBC...