The speed is having 1-15 level. That mean one minute can run how many steps. For the level 1, the speed is 20setps / 1 minute for the level 2, the speed is 30 steps/ 1 minute for the level 3, the speed is 40 steps / 1 minute. by 10 steps increase. The fast is for level 15, is 160steps for one minute.