Introduction: This is USB hub , and integrated USB to serial port function , suitable for 3 / 2 / B+ / Zero / Zero W. It make you the trouble of lack of USB port on your , expecially for zero . Features: 4 USB expansion ports, compatible with USB2.0 / 1.1 mission. USB to UART for for serial debugging Multiple indicators for easy access to power, USB to UART and USB expansion interface Operating voltage: 5V Product Size: 65mm × 30mm Fixed hole diameter: 3.0m color: blue Material: PCB Package Contents: 1 x USB Hub Extension Board ( not include ) 1 x Micro-USB Cable 1 x Micro-USB Adapter Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.