It is kinda like the stuff used for the headliner of a car. It is 1/8" thick and usually has a nylon cover on one side and exposed foam on the other. I found it at Joann fabrics, but only in black. Then my husband found some at an outlet but it has nylon on both sides. He misunderstood and got me 2 yards instead of one and it is 54" wide, so I have a life time supply! lol
I used the stuff he got for this project and it worked well. Gave a lot of body to the bag and isn't difficult to sew through. I do still want to try the others with the fabric on both sides to see if there is any difference. I do know that it doesn't seem to make the tote as heavy as the cotton batting made my oversized tote I took to New Zealand. That is heavy with nothing in it!!!!!