These FR coveralls are an excellent value, you won't find FR coveralls anywhere at this price. But keep in mind they run smaller.
I originally bought these in 42R, my usual size, but the torso and shoulder area were snug. My arm movements felt restricted. They're still usable, buy It doesn't allow comfortable freedom of movement if I were to do labor work. If they were to shrink (which I haven't washed yet), then they would be unwearable. I later purchased 44R and the fit was fine, they fit similar to my other coveralls in 42R size.
For comparison:
I tried my old 40R NOMEX Bulawark coveralls that I used when I was in my early twenties, the belly area is snug, but they still allow unrestricted range of motion in my arms/shoulders.
Then I donned my 42R (my usual size) thicker modacrylic blend Bulwark coveralls and they fit fine.
I also tried my 42R Workrite cotton blend coveralls and they fit snug, but not as snug as this model in 42R.
In summary, they fit marginally smaller that Workrite FR coveralls and at least one whole size smaller than Bulwark FR coveralls.
I must add, that the undersized fit is specific to this model, I have purchased Key's non-FR coveralls in 42R and the fit was not as snug as this particular model.
Despite being undersized, I still highly recommend them.