The xl-18 tri-axial activity monitor has 3-axis motion detection. it uses a digital accelerometer to track movement in all directions for an extremely accurate measure of your motion. it records your steps, distance and calories burned. the xl-18 has a motion indicator that shows the intensity of your movements as well as a 14-day memory. a detachable lanyard, internal clock, power save mode and battery life indicator also come standard. and it can be carried in your pocket, purse or bag.