So I normally only use my cuttlebug to emboss. However i recently purchased the Anna griffin cut and emboss dies and it states to use the rubber plate that it came with along with the two "B" plates. So it makes me wonder what is the "c" plate for? It seems like I never use it.
Yes, Spellbinders, QuicKutz, X-cut, Marianne Designs - all the thin dies need a C plate. Having said that, there is now a new thin plate that you can add to the second B plate that makes it the same thickness as the C plate. I haven't actually seen those, but maybe that's what your rubber mat is.