Just to add on bro Meor's reply,
I will also be concerned about will poor quality winders magnetizes my watches inside [With the motor and connected to AC power]. If im not wrong, good winders has this in mind during their design and build.
Nevertheless, I never had problem with my cheap RM 400 - wooden 4 slots, 6 watches winder for 3 years. Aside from the increasingly noisy rotors, and the peeling off of the faux leather wrapped cushion
