SwaddleDesigns Baby Sleep Set includes our most-loved Transitional Swaddle Sack and a coordinating cotton muslin Crib Sheet. The Transitional Swaddle Sack is ideal for babies who prefer to sleep with arms up, babies who are starting to rollover, and babies who break out of a traditional swaddle. The uniquely-shaped, ½-length sleeves are not full length, so when mitten cuffs are closed, baby’s arms will be flexed close to body for swaddle snugness. The foldover mitten cuffs may be worn open or closed. Helpful 2-way zipper with 2 zipper pulls. The zipper zips down from the neck to make it easy to place baby in the sack and zips up from the feet to make it easy to change baby’s diaper. Our soft, breathable and lightweight cotton muslin fitted sheet is fully elasticized, and designed to securely fit standard US crib mattresses of 28 x 52 x 6 in. The cotton muslin is pre-washed to increase softness and we use premium cotton yarns to increase durability and minimize pilling. Machine wash warm and tumble dry low. The TRANSITIONAL SWADDLE SACK allows baby to SELF-SOOTHE and promotes BETTER SLEEP and SAFER SLEEP; Perfect for babies who prefer to sleep with ARMS UP, babies who are starting to rollover, and babies able to break out of a traditional swaddle LITTLE SLEEVES with BIG PURPOSE; The 1/2-length, uniquely-shaped sleeves with mitten cuffs closed provide partial suppression of Startle Reflex to help baby SLEEP BETTER, and if baby rolls onto tummy, baby can push up to reposition head to access air EASIEST way to move from a traditional swaddle to a wearable blanket; The Transitional Swaddle Sack is not a tight swaddle nor a loose sack; the snug fit helps baby feel secure and the special sleeves allow baby to use their arms for SAFER & BETTER SLEEP HELPFUL 2-way zipper for easy diaper changes. Soft cotton knit. SNUG fitting design supports baby in natural flexed position. Small 6-14 lbs 0-3 Mo; Medium 14-21 lbs 3-6 Mo; Large 21-24 lbs 6-9 Mo; US Patent D883613 and EU China Patents Breathable crib sheet made using premium cotton muslin, pre-washed for softness; Sheet sized to securely fit standard USA crib mattresses of 28 x 52 x 6 inches. ASIN B0DM3Q68W9 Style Swaddledesigns Lrg Heather Gray + Jadeite Sheet Material Cotton Brand Name SwaddleDesigns