it is an air powered tool, that has is based on an air hammer, with a fiture on the end containing 11 to 17, hardened steel needles. They viberate and loosen the dirt, grease etc, from the steels surface. I believe that i got mine at Northern or one of those online stores. You can speed any amount of money on one up to 7 or 800 dollars. They make two kinds, one is straight, inline and the other is a pistol grip.
