Colors, S-XL - Blank. Port & Company (R) Core Cotton T-Shirt. An indispensable t-shirt in our classic silhouette with a very friendly price. 5.4-ounce, 100% cotton. Due to the nature of 50/50 cotton/poly neon fabrics, special care must be taken throughout the printing process. Athletic Heather is 90/10 cotton/poly. Dark Heather Gray, Neons, Heather Royal, Heather Navy, Heather Red, Heather Athletic Maroon, Heather Dark Chocolate Brown and Heather Purple are 50/50 cotton/poly.