Its the cardboard that is inserted into plastic bags for vintage comic books......supposed to be acid free. I ordered 100 the other day and begin wrapping my stash..almost used up all of them and need more. I only wrap uncut fat quarters, then 1/2 yd to 2yds. Less than fat qtr I fold and put in tray, more than 2 yds I fold and put in shelves.
delma