Dynamat Roller (makes application so lay smoother)
Crutchfield Customer Review (What's this?)
I would recommend that if you purchase Dynamat (any size) to go ahead and purchase the roller as well. It helps to seal out any air pockets. That may cause your dynamat to not stick fully to the part that you are applying it to.
Pros: It makes the application of the Dynamat, easier to stay down with any air pockets.