Track your activity levels with this FitBit Flex wireless activity tracker. The lime green color (which looks yellow only in photos) adds a pop of style to your fitness routine. This tracker is perfect for running and jogging, and can be worn both indoors and outdoors. The wristband feature allows for easy attachment and removal, and it is compatible with iOS operating systems. Made of durable plastic, this FitBit Flex is built to last through all your fitness adventures.