Help identifying sheets

So, I recently acquired a job lot of print/vinyl items from a closed business that (as far as I know) mainly did signage, vehicle graphics and some wrapping.

Amongst the items were a load of large plastic sheets, similar to that found on HTV backing, which are glossy one side and textured on the other.
I did wonder if they were some kind of lamination maybe? - Not something I've used before anyway.
If anyone has any ideas, feel free to shed some light...it'd be much appeciated.
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