A fantastic addition to any humbucker that needs a little extra push in output, and/or needs a bit more articulation.
These ceramic spacers slip in where your maple/plastic spacers usually would be under the bobbins, against the pole pieces of your humbucker. Slip them in repelling against the magnet on the other side of the pole and you they will increase the magnetic field strength at the top of the pole, underneath your strings - essentially like a mini P90. A stronger field strength will increase output and clarity - fantastic for pickups that are used under high levels of gain, or to remove some muddiness from the neck position.