Get Upto 30% Discount On Fitbit Flex Tracker At Kohls.com. Make fitness a lifestyle with Fitbit Flex, featuring FitStar to make sure one stay on track. It has free 3 month trial of FitStar Personal Training. The FitStar offers tailored workouts streamed straight to the phone, tablet or computer. The Fitbit Flex tracks steps, distance, calories burned and active minutes. The device monitors the sleep and wakes one with a silent, vibrating alarm. It set goals, view progress and earn badges with the free Fitbit app. The size of the product is 3 x 3.75 x 0.5. It comes with manufacturers 1-year limited warranty.