We just spent some time with the Fitbit Flex, the company's latest wristband-style fitness tracker. Announced earlier today, the device syncs in realtime with iOS hardware (and select Android handsets soon), and there's also an included USB dongle that will automatically upload your activity data to a nearby PC or Mac. Getting set up is simple enough; you just pop the tiny white tracker unit into a soft, colored wristband and go about your day. Aside from its core fitness monitoring, the Flex will also track the quality of your sleep each night and you can set alarms to wake you in the morning. Flex is water resistant and shower-ready; the company says it put the device through a number of tests to prove its mettle. Two sizes of the Flex wristband will be included in each box, so you it shouldn't take long to find the right fit. We found the latest Fitbit comfortable to wear and the LEDs were perfectly visible in bright sunlight. We're looking forward to giving the final version a thorough test this spring.