I'm trying to find a product I used in a digital printing course I took but I don't know its name and haven't had much luck with Google. It was a very thin transparent plasticy film that you could cut from a roll and place on your garment and seal with heat transfer. It added a completely transparent fairly matte plastic layer to the fabric. I liked the effect and want to find it again. It looked a lot like cling film though it didn't stick to itself.

Can anyone tell me what this is called and/or where I can find it?