CURVED DESIGN - Curved design with higher front and rear roller and lower center position makes it so when the user takes bigger steps the speed increases, with smaller steps the speed decreases, and when the user stands on the center, the treadmill slows to a stop. SLAT BELT DESIGN - Unlike a conventional treadmill, it uses thick and strong caterpillar type slats. There is no running board under the belt, therefore there are no concerns for shock to the human body while running." RUNNING ON NATURE - When the user take steps on the curve, it stimulates the body to start putting pressure into the big toe first, imitating the stimulation of running outside. Over 20- 30% more efficiency guaranteed." BLUETOOTH COMMUNICATION - Through Bluetooth communication (BLE4.0) and by DRAX designed smartphone APP, you can display all kinds of exercise information on your smartphone or LCD monitor. You can even manage exercise information with IoT technology. Bluetooth Included - This Cardio device includes bluetooth for more easier configuration.