Heather colors are 52% combed and ring-spun cotton, 48% polyester - Athletic and Black Heather are 90% combed and ring-spun cotton, 10% polyester - Solid Colors 100% pre-shrunk cotton - Fiber content may vary by color FOR THE BEST FIT; (See Size Chart in Images). 1) Lay a t-shirt on a flat surface. 2) Measure the chest area, just under the armpit from side to side to find the shirt's width. 3) Then measure the length from top of the shoulder to the bottom of the shirt to find the shirt's length. 4) After taking your measurements, match them to the closest sizes in the chart. HOW TO ORDER Choose your favorite design. Review the size & color charts above FIRST and then select shirt size and color from the dropdown menu. Please note size measurements for t-shirts may differ +/- 1 inch due to the manufacturer. Colors may not exactly match what's shown on screen. Thanks for stopping by my shop. Feel free to reach out for any questions you may have. I appreciate your business.