30# roofing paper Harold, same thing that the vendors are
going to be selling you.

There are several videos of the shrinking disc in use that were
posted by the guys that make and sell them. I've bought several
from different guys and if I remember correctly they all had a
video on the use of them.
One that I bought was not made very straight and it wanted to
hop all over the panel but he sent me another that was ok.

Here's one of those videos that show the disc for those that
have never seen it used:



DG

Denny G
Sandwich, IL