100% Pre-shrunk cotton. Short sleeve, crewneck, 4.2oz lightweight modern cut t-shirt, which means that it has a fitted cut. The heather grey shirts are made of a soft 90/10 cotton/poly blend. Ultra-thin shirts are a 3.4 oz tri-blend of 50% polyester, 25% cotton, and 25% rayon. This unique blend creates a soft, lightweight shirt that lasts. All other colors are 100% Cotton. We typically stock Canvas brand fitted cut shirts, think "American Apparel" Style. The Tri-Blend Ultra-Thin shirts are very thin and comfortable. If you want a looser shirt, please order a size larger than you typically wear. All of our shirts are printed on a state-of-the-art Direct to Garment printer, which gives you the highest quality vibrant graphic images. They are not "iron on" images that will flake off in a few washes, but are made to look as great 100 washes from now as they do right out of the package. Thank you and enjoy your shirt!