Baby Shusher uses a rhythmic "Shhh" sound to break a baby's crying spell. For newborn babies, this mimics life in the womb where babies hear tons of sounds throughout the day. It's much more effective than just using white noise.The Baby Shusher is wireless and portable, so it goes anywhere baby goes. Each device comes with a handy wrist strap making it easier to carry or tether to the car seat, and is ready to use right out of the box with 2 Aa Duracell Batteries.