There are 3 modes to check servos or ESC: Manual mode: turn the knob to adjust speed and check the reaction time; Neutral mode: return the servo to the neutral position; Automatic "window wiper" mode: make the servo swing to the maximum angle repeatedly. It can connect 1-3 servos simultaneously to test consistency and performance. It also supports connecting 1-3 ESCs for testing and comparing their reaction times. Compatible with 3 servos on CCPM helicopters for servo selection and setup. Can be used with airplane servos to install steering mechanisms and adjust control surfaces using neutral mode and other functions. Functions as a CCPM servo consistency tester and servo checker. The device can also serve as a signal generator for electric speed controllers (ESC). Enables testing of motor systems without requiring a transmitter or receiver. Package Contents: 1x tester. Note: Light and display differences may cause slight variations in color between the image and actual item. Measurement error allowance is +/- 1-3 cm.