Swaddlers with Lumi have been designed specifically for use with the Lumi by Pampers Smart sleep sensor (sold separately), which when used together help you learn, track and understand how to improve your baby's sleep. These touchable soft diapers are enhanced with a secure attachment area to keep the Lumi sleep sensor in place safely and offer the same trusted comfort and protection you expect from Pampers - the #1 U.S. Pediatrician recommended brand. The Lumi smart sleep sensor (sold separately) automatically tracks your baby's complete sleep 24/7, and gives you access to expert sleep coaching from leading pediatric sleep experts along with personalized insights & tips all available via the Lumi by Pampers app. Get a complete picture of your baby's sleep so you can build sleep nourishing routines that help the whole family rest easier, with Lumi by Pampers. Available in sizes N to 4. Umbilical cord notch (sizes N-2)