Sizes and measurements
Information regarding the N1 USN DECK JACKET jacket:
Choosing the right clothing size also means knowing how you'll wear the jacket. Will you be wearing a sweater, or a period uniform underneath?
You may need to order "one size up", depending on the thickness of the clothes worn underneath.

To best determine the fit, it can be helpful to compare the measurements of your garment to those of a similar garment you already own. Lay your garment flat and take all measurements from the outside.
Information regarding T-shirts: