NASA-grade temperature regulation and a 19x more breathable than cotton pique knit combine to make the most comfortable shirt on the planet. Features: Temperature regulating Phase Change Material Breathable, sweat-wicking pique knit Wrinkle resistant 57% Polyester, 43% PCM-infused Polyester Fit: Standard fit is 2" wider at the chest than our Slim Fit Care: Machine wash cold, tumble dry low. Naturally wrinkle resistant. Final Sale: All Capsule sale items are final sale and not eligible for returns or exchanges. FAQs here. Size Guide: Apollo Shirt XS S M L XL XXL XXXL Chest - Slim (Body) 33-35 35-37 38-30 42-44 45-47 48-50 51-53 Chest - Standard (Body) 35-37 37-39 40-42 44-46 47-49 50-52 53-55 Sleeve Length (Garment) 31-32 32-33 33-34 34-35 35-36 36-37 36-37 Body Length (Garment) 29.5 30 30.5 31.5 32.5 33.5 34.5