Features: 1.IO: bit expansion board is a expansion board, which leads to 19 PIN pins of the Microbit Board. 2.Each PIN pin has VCC and GND corresponding to it. You can freely switch VCC to 3.3V or jumper cap. 5V; with 3 3V3 and 5V pins, the wiring is more flexible and diverse; 3.I2C SDA and SCL pins and the corresponding 5V and GND pins are provided for module connections such as LCD1602 LCD display for I2C communication more possibilities; 4.With on-board passive buzzer, connected via jumper cap; 5.Power supply includes DC head and USB socket power supply. Parameter: PCB board thickness: 1.6mm Small round hole diameter: 3.0mm round hole diameter: 4.6mm (compatible with holes) Product Size: 57mm / 39mm / 15mm USB input voltage: 5V DC head input voltage: 6-12V Material: pcb colour: black Package Contents: 1 x Expansion Board Only the above package content, other are not included. Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.