They are OEM on the Brembo set up as they are glued to the rear of the front Brembo pad.
that can't be classed as a shim then in the true sense of the word (pedantic I know .....sorry) they are an integral part of the (well designed) pad
Wiiki says:
"A shim is a thin and often tapered or wedged piece of material, used to fill small gaps or spaces between objects. Shims are typically used in order to support, adjust for better fit, or provide a level surface. Shims may also be used as spacers to fill gaps between parts subject to wear."
I rest my case m'lud