Features:

The device  can be used as a signal generator for servo motors testingor for  electric speed controller (ESC), then you can test your motor system without using a transmitter and receiver.

There are 3 modes to check servos or ESC:
Manual mode: turn the knob with different speed, check the reaction time.
Neutral mode: make the servo go back to the neutral point.
Automatic mode: make the servo swing like a window wipers in the biggest angle.

It can connect 1-3 servos simultaneously and test such as 1-3 servos consistency and so on.
You can also connect 1-3 ESC to test and compare their reaction time respectively.

Specification:
Voltage consumption: DC4.8-6V
Size: 48 x 42 x 17mm
Color: Blue
Net weight: 7g