Give wings to your Particle Core or Photon using this stackable piggyback board.
Use this to connect extra wires, headers, LEDs to a Photon or Core already mounted in an existing project/PCB.
I use this to connect the Programmer Shield to a Photon in an existing circuit.
Solder a row of 12-pin stackable headers or 2 6-pin stackable headers to each middle column of holes (the one bordered by the white rectangle).
Then solder other wires, headers, etc to the other columns of holes.