But as I understand the strops should only lay on the flattening plate. Is the friction between the strops and the flattening plate large enough to avoid that the strops do not slip when stropping. I see that some of the strops have a magnetic back, and assume that it have to be a reason for that.
I have that same set. The base has a metal plate. The leather and balsa pads have magnetic backing on them and attach to the base. No slipping that way. It's a great setup and will serve you well. You can get more pads for it too.