Single 100% cotton muslin sleeping bag. aden +anais sleeping bags are designed to be worn over a baby?s pajamas, ensuring a safe night?s sleep by eliminating loose crib blankets, which can be dangerous. Muslin?s light, open weave allows a baby?s body temperature to regulate itself naturally helping to prevent overheating. aden + anais sleeping bags offer the ultimate in breathability and softness, as the more the more you wash them, the softer they get. Each sleeping bag zips from the bottom, making diaper changes easy, and a strip of muslin over the zipper by baby?s face provides extra comfort. aden and anais award-winning sleeping bags are the perfect sleepwear to follow our popular swaddling blankets.