Activity Monitors features: Chronus Fitness Watch, Activity Trackers with Heart Rate Monitor and Sleep Monitor(Gray) Color: we send based on the color or size of the main image of the product page. Quantity：we send based on quantity on title, if there is no quantity in the title, we send based on description. Easily Tracking Your Daily Fitness: Not only can track your daily activity from day to night, like running, riding, hiking, but also can record your basic data, like steps, heart rate, calories burned, walking distance, etc. The waterproof function above IP68 can even let you take the sports smart watch for swimming. Moreover, the vibration alert motivates you to move when you've been sitting too long. Monitor Your Heart Rate, Blood Oxygen & Track Your Sleep: Fitness trackers automatically monitor your real-time heart rate, blood oxygen and provide comprehensive analysis of your sleep quality (deep sleep, light sleep and wake up time) to get a better understanding of your health status at a glance and make timely adjustments. See Calls & Messages on Your Wrist: Conveniently receive call, calendar, SMS and SNS (Facebook, WhatsApp, LinkedIn, Instagram, and Twitter) notifications on activity trackers; never miss the messages that matter. Moreover, When you are doing exercise, the music can be controlled directly on your wrist. The fitness tracker is compatible with smartphones with iPhone iOS 8.0 / Android 4.4 and higher. (Note: Except iPad / Tablet / Laptop) Alexa Built-in: Easily press the touch key to go to Alexa voice control, speak your request on the devide. You can use alexa to chat, Wikipedia, check the weather, Amazon shopping list and other information, set alarms, countdowns, stopwatch functions, and event reminders. (please log in your amazon account before use) Long Battery Life & Lifetime Warranty: Just remove the band then plug on USB port to charge the fitness tracker.