This is an accelerometer based on iPhone. Especially it can measure the accelerations of iPhone and its paired Apple Watch simultaneously, and plot the 3 axes figures for them in real time. In addition the data flows collected by Watch are transmitted to iPhone via Bluetooth synchronously for graphic display. On top of that, for both devices the sampling rates may be set separately (5-50 Hz). As a result users could explicitly perceive the distinct sensitivities of sensors in different frequencies. Specifically, the sampling rate of the accelerometer in iPhone could be varied by the Slider on iPhone’s interface dynamically; while that of Watch might be adjusted in 3 ways: the Slider on Watch, the digital crown, or the Slider on iPhone side. With this App the detailed kinetic characteristics of both devices would be totally at your fingertips!