Fitbit Flex 2 Wireless Activity Monitor, Sleep Counter 。Brand New In Box, never opened Fitbit Flex Wireless Activity + Sleep Wristband, Black, Small/Large, Two Wristbands Included (Large (6.5-7.9 in) & Small (5.5-6.5 in) Accessory bands allow you to personalize your Flex; Easy-to-wear, slim, comfortable wristband; Free Apple iPhone and Android app; Instantly launch your Fitbit app by tapping your device your NFC-enabled Android phone; LED lights show how your day is stacking up against your goal; Log food, weight and more on Fitbit\'s website or apps; Monitors how long and how well you sleep; Rechargeable battery; Set goals, view progress and earn badges; Share and compete with friends throughout the day; Syncs automatically with select mobile devices and to your computer; Tracks steps, distance, calories burned and active minutes; Wakes you (not your partner) with a silent wake alarm; Wear in the shower; Wear proudly all day and night.