There are 4.
Foam, formed to fit. 140, 210 fronts, 203's
Plastic, just like a kitchen garbage bag. 126, 124's
plastic with 1/8" jute on it. 124's, early 210's
Some weird looking stuff that is a insulated clotch stuff..... ML's have it. 163's and I think the G class as well.
Ok, so this is off the top of my head on Sunday morning before my 2nd cup of coffee. If I'm wrong so be it.
If you want to quiet down a 201 a bit, get some 1/8" jute and glue it to the outside of the lower portion of your vapor barrier.