Cotton Helps your baby sleep safely and you sleep without worry Unique sleep swaddler comfortably secures your baby on their back during sleep (which is recommended by the American Academy of Pediatrics) Reduces risk of rolling over, tummy sleeping and falling or climbing out of the crib; Easy to secure to your mattress and baby with Velcro Ideal for babies with reflux when used in conjunction with a crib wedge Fits all standard size crib mattresses & mini-mattresses. Machine washable; 100% cotton; Recommended for babies 0-9months/7-25 lbs