1. Please make sure the output voltage your device uses is within 15v to 24v. You can find the output voltage on your laptop or the original ac adaptor that comes with your device.
2. Find the correct connector by trying to plug it in the device. We recommend plugging the connector in the device before it is plugged into the AC Adapter.
3. Select the correct voltage (determined by your laptop) just by simply moving the voltage switch button with your finger.