Best Heart Rate Variability Tracking

Mio Slice Heart-Rate-Monitors, Sienna, Small

PAI is Personal Activity Intelligence, a scientifically-validated metric showing how much activity you need to do to stay healthy..
Get heart rate intensity feedback with PAI technology, tracking all activities even those that don't involve steps..
Accurate continuous heart rate tracking, 24/7. Also tracks steps, distance, calories burned and sleep as well as displays smartphone notifications..
Compatible with select smartphones: iOS 9.0 and above (iPhone 5S or newer) and Android 5.0 and above (Google Nexus 5, 5x, 6, 6p.

PAI is Personal Activity Intelligence, a scientifically-validated metric showing how much activity you need to do to stay healthy..
Get heart rate intensity feedback with PAI technology, tracking all activities even those that don't involve steps..
Accurate continuous heart rate tracking, 24/7. Also tracks steps, distance, calories burned and sleep as well as displays smartphone notifications..
Compatible with select smartphones: iOS 9.0 and above (iPhone 5S or newer) and Android 5.0 and above (Google Nexus 5, 5x, 6, 6p.

PAI is Personal Activity Intelligence, a scientifically-validated metric showing how much activity you need to do to stay healthy..
Get heart rate intensity feedback with PAI technology, tracking all activities even those that don't involve steps..
Accurate continuous heart rate tracking, 24/7. Also tracks steps, distance, calories burned and sleep as well as displays smartphone notifications..
Compatible with select smartphones: iOS 9.0 and above (iPhone 5S or newer) and Android 5.0 and above (Google Nexus 5, 5x, 6, 6p.

PAI is Personal Activity Intelligence, a scientifically-validated metric showing how much activity you need to do to stay healthy..
Get heart rate intensity feedback with PAI technology, tracking all activities even those that don't involve steps..
Accurate continuous heart rate tracking, 24/7. Also tracks steps, distance, calories burned and sleep as well as displays smartphone notifications..
Compatible with select smartphones: iOS 9.0 and above (iPhone 5S or newer) and Android 5.0 and above (Google Nexus 5, 5x, 6, 6p.

PAI is Personal Activity Intelligence, a scientifically-validated metric showing how much activity you need to do to stay healthy..
Get heart rate intensity feedback with PAI technology, tracking all activities even those that don't involve steps..
Accurate continuous heart rate tracking, 24/7. Also tracks steps, distance, calories burned and sleep as well as displays smartphone notifications..
Compatible with select smartphones: iOS 9.0 and above (iPhone 5S or newer) and Android 5.0 and above (Google Nexus 5, 5x, 6, 6p.

PAI is Personal Activity Intelligence, a scientifically-validated metric showing how much activity you need to do to stay healthy..
Get heart rate intensity feedback with PAI technology, tracking all activities even those that don't involve steps..
Accurate continuous heart rate tracking, 24/7. Also tracks steps, distance, calories burned and sleep as well as displays smartphone notifications..
Compatible with select smartphones: iOS 9.0 and above (iPhone 5S or newer) and Android 5.0 and above (Google Nexus 5, 5x, 6, 6p.

Heart Rate :24hours real-time continuous heart rate monitor per munite to know your conditions.
Blood Oxygen: Automatically Measure the blood oxygen saturation from 0:am-7:0am,let you know the respiratiory rate.
Scientific Sleep: all-weather sleep tracking ,even in a naps over 30minute ,there will record your sleep quality like deep and ligh sleep time ,sleep duration..
HRV : tracking the heart change condition at night time and alert it for care.
Warranty: one year guarantee and online technical support always..

DAY & OVERNIGHT HEART RATE - Enjoy heart rate tracking day & night plus continuous tracking during workouts..
DAILY ACTIVITY TRACKING - Automatically counts steps, calories and distance..
AUTOMATIC SLEEP MONITORING - Wake to a Sleep Score based on light & deep sleep cycles, interruptions, depth & regularity..
MULTISPORT TRACKING - Tracks 30+ sports and maps your session with distance, elevation and pace via connected GPS..
RECORD BATTERY LIFE - Spend more time moving and less time charging with a rechargeable battery that lasts up to 25 days..

...ification】: You can get call,SMS messages and SNS notifications directly on your wrist(including Facebook, Twitter, WhatsApp and Instagram)..
【Heart Rate & Sleep Monitor】：Measuring your heart rate on every 1 / 2/ 6 /12 hour automatically once you set up it in the app. You can also set up real-time heart rate tracking or manually tracking. Or you switch watch to heart rate interface, it will also automatically monitor your heart rate within 30 seconds (Measurement results are for reference only, not for medical use)..
【Fitness Tracker with 6 Sport Modes】：Switch 6 different sport modes on watch directly. Built-in advanced 3D sensor and pedometer to accurately count your steps, calories burned & distance achieved. Steps: 1. Long press to choose which kind of sport, 2. long press again to enter sport mode, it will count 3, 2 ,1. Then you can start your excerise..
【Direct USB Charging】: Fast charging the bracelet by USB port without cable, and the 80mAh rechargeable battery can working standby time for 7 to 10 days.
APP support Above Android 4.4, Above iOS 8.0, Bluetooth 4.0.Please download Flagfit 2.0 app to connect it..

...se activity fitness tracker with 11 built-in sports modes, enabling you to record the distance, speed, heart rate changes, calories burned, and other data during your workouts. With a water-resistance grade of 5 ATM, Band 5 can withstand all your daily activities and you can wear it while swimming..
WOMEN’S HEALTH TRACKING: With the female period tracking system, Band 5 records and predicts the female menstrual cycle and sends smart notifications reminders..
COMPATIBLE PHONE MODELS: Android 5.0 or iOS 10.0 and above..