Cotton 100% ORGANIC COTTON: Crafted entirely of preferred cotton fibers grown without chemicals, pesticides, or GMOs. CERTIFIED GOTS (Global Organic Textile Standards): Meets stringent environmental criteria along the entire supply chain, as well as some of the world's strictest social responsibility standards LIGHTWEIGHT & BREATHABLE: Muslin weave allows for air to flow freely to reduce the risk of overheating, while still keeping your babe cozy SOFT & STRONG: Durable muslin cotton withstands countless washes and softens with every cycle. Wash cold and hang or tumble dry low CUSTOM FIT: Uniquely designed for a 360-degree fit on the Babyletto All-Stages Midi mattress or pad (35.8”x 28”x up to 4”)