WWMDiB 4Pcs RC servo Tester with 3 Modes to Check servo or ESC, able to Easily detect and configure Server Virtual Space, Jitter and Median, servo Controller

I checked all 4 of the testers on receipt and they all work for my purpose (as a throttle control). I connected them to the throttle output from my brushless ESC and then used the knob to start and run the brushless motor. I checked all 3 outputs as well as the input separately. I had originally connected 4x AA batteries to the input which powered on the testers. However, I noticed that when connecting the ESC's throttle output to the tester's output, I did *NOT* need any power connected to the input side as it seems to draw the power provided by the ESC connector.So, in case anyone's wondering how to use these (as there aren't any instructions provided), you only need your ESC, motor, RC battery and the tester. Make sure the tester's knob is in the lowest position. Connect the ESC to the motor and the ESC's throttle lead to one of the servo tester's *outputs*. If it's an RC plane/drone motor, make sure there isn't any prop connected to the motor. Now, connect the ESC to your RC battery. When you slowly turn the knob, it should start the motor and the knob will act as a throttle control. I haven't tested the other modes of the tester to see if/how they work.

Tool the time to have the potentiometers of each of these professionally replaced, just to find out not a single one even will power up, so disappointed!!!!

They work but the plastic cover shifts easily and it is a bit hard to plug in the wires but it is also very cheep and if it works and it is cheep it's a win