Real-time Tracking - Monitor, track and record oxygen levels and heart rate every second continuously Audio Reminder - Audio reminder for low blood oxygen in mobile APP & device; Adjustable alarm volume & threshold Wearable - Gentle & breathable fabric provides a comfortable wearing experience like a sock Free iOS/Android APP - Pair by Bluetooth 4.0; Track real-time data, review history records & receive alarm instantly Rechargeable - Built-in rechargeable battery with approx.16 hours battery life IP22 For Baby 0-3 years old