Here I don’t see what you mean. The mast is sitting on a threaded rod going trough the main beam (12mm hole) with a spacer between the upper and the lower walls of the beam. This rod is screwed into a nut welded on the tube going down straight to the strap. So if you want, I can by unscrewing the tube a little lift the mast foot free of the beam by tightening the strap and put no strain on the beam at all. The other edge is maybe RG, I have the feeling that he is going without a striker at all and just using the walls of a bent alu tube.