Sleep SackKeeps infants safe and snug during the transition away from swaddling. Slightly weighted quilted design promotes restful sleep. Reinforced stitching provides durable, long lasting quality. Combines current sleep safety research with soft plant based fibers. Soft, breathable fabric plus weighted quilting supports optimal sleep. 2 way zipper allows fuss free changes at any time of night. YKK zippers are durable, smooth, and non toxic for delicate skin.