Released in November 2020, the Raspberry Pi 400 is actually a Raspberry 4, but built into a keyboard, with the GPIO expansion connector on the back of the enclosure. Connecting additional hardware always brings risks, especially during prototyping. The buffer board we present here is especially designed for the Raspberry Pi 400. It enables interfacing with both 3.3 V and 5 V external logic for all the 26 GPIOs, and the buffers/level shifters used for this also provide ESD protection.