Unique patented wings allow natural ARMS UP position ARMS UP allows true SELF-SOOTHING = more sleep Swaddle in seconds with no breakouts Twin zipper for easy diaper changes No loose layers to kick off during sleep Acknowledged as a hip-healthy product by the International Hip Dysplasia Institute; design allows the recommended flexion for hips & legs Our original jersey fabric is a soft, stretchy knit. Made to last, wears well and retains shape wash after wash