Overview:

Tracks steps, distance, calories burned and stairs climbed
Monitor how long and how well you sleep
Wakes you (and not your partner) with a silent alarm
Syncs automatically to your computer or select smartphones and tablets via Bluetooth 4.0
Set goals, view progress and earn badges
Sync stats wirelessly and automatically to your computer and over 150 leading smartphones
Fitbit One:

Wireless Activity + Sleep Tracker

If you want to turn fitness into a lifestyle, the One is for you. For starters, it never rests. During the day, it tracks your steps, distance, calories burned, and stairs climbed. Come nightfall, it measures your sleep quality, helps you learn how to sleep better, and wakes you in the morning. The One motivates you to reach your goals by bringing greater fitness into your life – seamlessly, socially, 24 hours a day.

Activity tracking
Clock + display
Sleep + alarms
Wear + water-resistant
Features:

Online & mobile tools

Syncs stats wirelessly and automatically to your computer and 120+ leading smartphones – including Android, iOS and Windows.

Set goals, log food, see progress, analyze trends and earn achievement badges through your mobile and online dashboard.

Share and compete with friends and family on the leaderboard and in new Fitbit challenges.

Activity tracking

Track steps taken, floors climbed, distance, calories burned and active minutes.
Clock + display

See daily stats and time of day on the OLED display.
Sleep + alarms

Monitor how long and how well you sleep and wake with a silent alarm.
Wear + water-resistant

Clips securely on clothing, is water-resistant and has a rechargeable battery that last 10+ days.
What's In The Box:

Fitbit One™ tracker
Charging
Wireless sync dongle
Silicon clip
Sleep wristband