JUST4YOU SYSTEM APP is used to control the steady and continuous output of electrical pulse of smart box. EMS technology is to simulate human brain electric signal to stimulate motor nerve with the low frequency pulse current. Through controlling the pulse current safety regulation such as frequency, interval time, time, and adjusting the contraction of muscle strength, EMS can command group muscles to work together, achieve development of muscle strength, reduce fat in shape, and realize the treatment of muscle tissue injury.