Zuma Jays passionate about using sustainable, & environmentally friendly materials in our products when we can. No GMO's are used on our garments resulting in a softer cotton, trust us you'll notice the difference! This sweatshirt is quite a tight fit, so we would recommend the next size up from what you normally would unless you like a tight fit. Size Guide: (chest in inches) Small: 38" Medium: 40" Large: 42" X-Large: 44" 254446