macojoe: I'm 6'4 235 and it fits tight on me but my diver captain friend says they are supposed to fit tight. After a little practice I can get it on and zipped up in less than 30 seconds..I would doubt if you could get into it if you go 350 . The other one I got was an Xl and it fits my friend who is 6 foot even and about 200. Most of the language on mine is in french but it has the size XXL and some instructions in english but no other measurements..I dont know if they make an XXXL or if any of the other companies make one but I am very satisfied with mine..its one of the few marine things I've bought that actually does what it says it will do..I would guess they are pretty expensive if you were to buy a new one...Most of the suits that I looked at on ebay were medium to large so I lucked out as this one is a real XXL and I wear 2x shirt so if you could find an XXXL it would probably fit. I saw a special on alaskan king crab fishermen a while back and some of those russian american fishermen were big guys so someone makes them big...Frank