WHAT DOES PUREBRED MAINE COON CATS FOR SALE MEAN?

I obtained her from the rescue shelter plus they didn’t even know the sort. The vet says medium hair domestic cat but she's humongous and has really quite coat. I’m thinking about getting her examined to see.Details and mask blue with slim band of white hairs beside skin which can be witnessed only when fur is parted. White frill and ear tufts.