From website: . A wearable blanket that helps baby fall asleep (and stay asleep), so you’re not up all night. Designed to be safe sleep, diaper change friendly, temperature-regulating, and so soft you’ll have to touch it to believe it. Exterior: 97% Rayon made from Bamboo, 3% Spandex Filling: 100% Polyester Highly breathable J-shaped double zipper Use as a wearable blanket over pajamas for safer, cozier sleep