Sizes small and medium in gray and large in black fit as expected, but check out the manufacturer's size chart here to ensure you order the right size.
Sizes Large to 3XL in gray run very small (between 1-2 sizes different that what you normally wear), so please size up. Check out the manufacturer's size chart here. (And if you need something larger, check out the unisex shirts, which are generously sized and very comfortable).
Black shirts are 100% cotton. Grey shirts are 65% polyester/35% cotton.
*Dog not included.