Fitbit Flex Wireless Activity and Sleep Tracker Wristband - Black
Model #20W-S16-FB401BK

As low as $20 / month

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The black Fitbit Flex Wireless Activity and Sleep Tracker Wristband is a water resistant band that you wear on your wrist to track vital daily stats. It tracks your steps taken, distance, and calories burned. It also measures your sleep quality and has a silent alarm that vibrates to wake you up - rather than beeping which could wake others. The Flex features Bluetooth 4.0, so it syncs wirelessly with your devices automatically whenever it is within 20' of them. Both a small and large wristband are included to ensure a comfortable fit, as well as a wireless sync dongle and charging cable.


  • Fitness Tracker Wristband
  • Tracks Steps, Distance, Calories Burned
  • Measures Sleep Quality
  • Bluetooth 4.0
  • Syncs Data Wirelessly
  • Vibration Alarm for Waking
  • Works with Companion App
  • Large and Small Wristband Included


  • Transceiver Interface Type: Bluetooth 4.0 (for wireless syncing)
  • Syncing Distance: Up to 20.0' (6.1 m)
  • Water Resistance: Yes, can be submerged up to 32.8' (10.0 m)
  • LEDs: Flex uses five white LED indicator lights to show you how your day is stacking up against your goals. Each light represents 20% of your goal. Just tap the display twice to see your progress against your daily goal
  • Sensor: MEMS 3-axis accelerometer measures your motion patterns to determine your calories burned, distance traveled, steps taken, and sleep quality. Its altimeter measures stairs climbed
  • Motor: Cylindrical vibration motor allows it to vibrate when alarms are set to go off
  • Memory: Fitbit recommends syncing your data regularly. As long as Flex has battery power, it tracks the most recent seven days of minute-by-minute data. It also tracks your daily total for the past 30 days and summarizes your daily calories, distance, and steps taken
  • Battery Type: Lithium-polymer
  • Battery Life: 5 days
  • LED Indicators: When charging your Flex the LED lights will indicate its level of charge. All 5 lights will light up when it's fully charged
  • Operating Temperature: -4 to 113° F (-20 to 45° C)
  • Storage Temperature: -22 to 140° F (-30 to 60° C)
  • Altitude: 30,000' (9,144 m) (maximum operating altitude)
  • System Requirements: Operating Systems: Windows XP/Vista/7/8, USB port , Internet connection | Mac OS X 10.5 and up, USB port, Internet connection | Supported browsers: PC: Chrome 12 and up, Firefox 3.6.18 and up, Internet Explorer 8 and up | Mac: Chrome 12 and up, Firefox 3.6.18 and up, Safari 5.0.5 and up
  • Dimensions: Small: 5.5 - 6.9" (140 - 176 mm) | Large: 6.3 - 8.2" (161 - 209 mm)
  • Width: 0.6" (15.2 mm)
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