Depends on what you get. If you get a decent one made with properly softened hides they are pretty flexible. Cheap ones not so much. Either way make sure you try it on first, and make sure its a bit on the large size for best fit. As for warmth, yes, very warm, almost too much unless you plan to be in sub zero temps for extended periods. If thats too much you can look for a B6. Its quite similar to the RAF pattern jacket with the pile cut to about half the length of a B3. Just FYI, what most vendors call a B3 is actually the RAF Irvin pattern. The B3 has a single map pocket on the right side, the RAF jacket has diagonal slash handwarmer pockets on both sides.