Where can I locate the serial number? GVIDO Customer Support 09 April 2018 04:03 Updated It is listed on the microSD card tray. Related articles Can you buy back my old device when you release a new device? Who should I contact when I need technical support for GVIDO product? What is the Support Center's operating hours? Does it require a Bluetooth or a USB cable to connect GVIDO to the foot switch? Can it be used immediately after purchase?