For Expansion Board Base Quick Prototyping:Easy debug and Reset with RESET button and SWD pin led out to the male header. 0.96inch OLED, enables visual data to display without PC serial monitor. Rich peripherals:OLED display, , expandable memory space, passive buzzer, user button, on board battery management chip etc. One board on hand to explore the infinite possibilities of XIAO series. Mini Size:Compact and elegant with only half for 4 size, perfect for tiny and wearable projects. No Soldering Needed:All pins are led out. Convenient plug-and-play Grove connectors support multiple data protocols, including IIC, Uart, and Analog/Digital. Circuit Python Supported:Well supports circuit python. Mini SD card slot enables memory space expansion, making it possible to allocate more libraries needed in prototyping and project building. Colour:As Shown Material:PC Package Contents: 1 x Expansion Board Base(Due to different product batches, the appearance , which does not affect the use) Only the above package content, other products are not included. Note: Light reflection 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.