The NORA Smart Sock is (1). The Most Comprehensive: The NORA Sock has the most comprehensive readings. It tracks all: the heart rate (for sleep tracking and training purposes), the feeling temperature, the sleeping position like on-back or on-stomach, and the sleep history. (2). The Accuracy: Thanks to the high accuracy of the readings, like the heart rate, tighter normal zone, 70 to 160 BPM, is defined. It's so good that you can even catch a baby's higher heart rate during feedings. (3). Reliable Connection: It doesn’t require any WiFi or base station. It connects to your iPhone directly over Bluetooth. (4). Use Anywhere: Thanks to the direct Bluetooth link, you can use it anywhere. Enjoy road trips or even flights with NORA keeping an eye on your little baby.