Fitness tracker Fitbit will introduce a new model this spring and it is designed for those who aren’t exactly rigid about their routines. As with other trackers the Fitbit Flex, which will arrive this spring, is designed for wearing on the wrist, and it is designed to track steps, distance traveled, calories burned, active minutes and quality of sleep. All of this can be synced to a user’s iPhone or Android drive via Bluetooth 4.0. It can even nudge wearer’s out of deep sleep with a gentle vibration.