600TC 100% Cotton 4pc Jersey Pocket Sheet Set

Are these 600 single ply? Or more like 150 thread (but counting each ply as a separate thread?)

I don’t get the Jersey pocket thing. It’s a fitted sheet, right? And as far as being green certified, wouldn’t it be a lot more green if it was made in this country, instead of being shipped halfway around the world?

This is a 4pc set, not just the fitted sheet.