Follow up question before I describe more: do you know where to buy the skin units?

I've seen the poly around wigs - although didn't know what it was called until now - but that's not what's on my wigs. When I first get them, they're all lace except the mono top, and then I or the orthodox Jewish woman I purchase them from sews in a thin fabric where I want to be able to tape it to my head. I've seen "skin units" made of thin poly but that's not it either - it comes in a big sheet that I can cut up to the size I need.

The more I ask around, the more I think it might just be a fabric from a fabric store. I could probably use the skin units to serve the same purpose; I have a few lying around from when I first got a wig through someone who makes them for Broadway shows.