This sleep sack has stretchy sleeves that support a natural sleep position allowing arms to move up out or anywhere in between and the roomy sack supports natural leg movement and proper positioning. The patent pending design with unique sleeve construction and stretch fabric helps ease the startle reflex while still allowing natural movement for self soothing. The snug zone creates a cozy held feeling that can help your little one settle for sleep. Unlike traditional swaddles discontinuing use is not necessary if your little one starts to roll. It balances movement and comfort to help little ones settle more easily for deeper more restful sleep and a two way zipper makes nighttime diaper changes quick and simple.