One of the things that makes Raspberry Pi’s small and inexpensive single-board computers interesting is the 40-pin connectors that makes it possible to connect expansion boards called HATs (which ...

The Raspberry Pi’s venerable 40-pin header and associated HAT ecosystem for upgrades has been a boon for the platform. It’s easy to stack extra hardware on to a Pi, even multiple times in some cases.

By taking I/O expansion boards directly off the Raspberry Pi, PiRack also enables the Pi camera module to be easily used in parallel with expansion boards that control motors or host sensors.