It just arrived today! This is a Womens Falke Dayton size M, he probably could've gone smaller but it does fit pretty well! He is 5'7", 5'8'', 161 lbs..
no sewing on the sleeve, he will just wear another grey undershirt under it. I'm not sure what his chest size is, I'll have to ask him! He has a 40 chest and this shirt is a medium, he thinks he could use a small, but it works for now.
My husband got lucky and got it from Amazon UK, but they are not there anymore. I think the others are getting theirs from Germany via Germany RPF members.