The Smart Sock 2 enhances everything that our 100,000+ parents loved about our original Smart Sock. It uses proven technology (pulse oximetry) to track your infant's heart rate and oxygen levels from the comfort of your home. The Smart Sock 2 has a range up to 100 ft and a new fabric sock design to ensure a comfortable fit and accurate readings. Our updated smart phone app makes it easy to view your baby's heart rate and oxygen levels in real-time. A smarter, more reliable sensor Pulse Oximetry: Updated pulse oximetry algorithms increase the precision and accuracy of your baby’s readings. Flexible: Our updated sock sensor is flexible and designed to adapt to your baby’s foot as he or she grows. A redesigned sock - soft, simple & secure Comfortable: Hypoallergenic cotton gently yet securely wraps around your baby’s foot and designed to grow with your infant. Sure Fit Technology: Innovative new sock design offers a more secure fit and intuitive placement, meaning more accurate readings. Universal Fit: Updated fabric sock can be worn on either foot, allowing parents to alternate as needed. Better Bluetooth, better base station Increased Range: Improved Bluetooth range, up to a 10x increase (100 feet), between the Smart Sock 2 and Base Station. Notifications: Improvements in hardware resulted in 4x fewer red and yellow notifications. More data, less worry Mobile App: Improved interface with sock sizing guide, push notifications and real time access to your baby’s heart rate and oxygen levels. Connected Care: Smart Sock 2 is compatible with Connected Care, an app that allows you to track historical data, red notification information and sleep trends.