To replace the batteries in your Rotor One watch winder, follow these simple steps:Unscrew the cover at the back of the winder and remove the battery compartment lid.Remove the used batteries and insert two new batteries, ensuring the correct +/- polarity.Caution: Incorrect insertion can damage your winder.Replace the battery compartment lid and screw the protective cover back on.With new batteries, your Rotor One watch winder will operate continuously for approximately 3 years. Note that low temperatures can reduce battery life.