This tracker features Amazon Alexa for voice commands and smart home control. It offers a 15-day battery life on a single charge, reducing the need for frequent recharging. The device includes a Blood Oxygen Saturation Monitor and 24/7 heart rate and sleep tracking with the BioTracker TM2 PPG sensor. The price drops from $39.99 to $19.99. Shipping is free for prime members. Otherwise, it adds $6.