I have tried it anyway and of course I have to warn you: It falls extremely small (I'm usually so normal between M and L)!
With 78kg I'm not willowy, but not fat, but I had to get in trouble in size M at all ... the whole thing was then vinous like a second skin, but rather as a lacing corset and I have endured less than 2 minutes in the part ,
That's very sad, actually the shirt had me very committed and the substance, and the processing can be nothing to be desired.
It is already clear that the shirt should be very narrow-cut, but nevertheless I recommend to order 1 size bigger than usual - as I said "M" Complies rather "S", if not "XS".
Apart from that, the quality is fine.