Looks like a meat tenderizer. As said above, it wouldn't be good to use with any deadener that has a foil (or I guess mylar) constraining layer. I dont think Id even want to use it on asphalt based mat, as it seems it would leave alot of places that receive little to no pressure was applied (between the teeth).
A simple wooden roller works best. And no, using your hands or even a screwdriver handle does not work as well. Sometimes you must employ other techniques like those in addition, but always always roller your stuff down, every last inch. The more you roller it down, the more it sticks. The better its stuck, the better it works.