Use this little GPIO header in combination with a 40-pin stacking header to use the Raspberry Pi PoE HAT with another addon board. This header goes on the 4-pin header of the Raspberry Pi.
Connect your own PCB to a Raspberry Pi and stack on top with this normal-height female header with extra long pins. The female header part is about 8.5mm tall, good for small HATs that do not to clear the USB/Ethernet jacks. This header has extra long 10m
For most applications, 1GB of RAM is sufficient, especially if you have a specific application for the Raspberry Pi where little multi-tasking takes place.