I know this was posted a long time ago but I have researched this and found the answer so I'm hoping to help other's out searching for the same thing. I contacted Cotton Heritage for the answer. There is a small tag inside the shirt close to the bottom on the side that has another number. It's MC1082 and if you go to their site at www.cottonheritage.com you should be able to find it there or at this link 100C Men's Crew Nk T 5.5oz. Cotton HeritageCotton Heritage