WTB Flight Jacket CWU 36/45 - Sz 38-42

[lefty12]

Interested to buy a decent flight jacket with a preference for CWU 36 or 45.
I wear a 38s so I'm guessing Sz 38-42 (Medium?) would be a decent fit.

Thanks

 

[Bfd70]

What does cwu 36 or 45 mean?