Little Brother Onesies & Tees. Natural color is a super soft 100% airlume combed ring-spun cotton (pre-shrunk). Heather Stone color is a super soft blended fabric tee (52% cotton / 48% polyester). Sizes smaller than 2T (3/6 months, 6/12 months, 12/18 months, and 18/24 months) are printed on onesies.