IMHO, The air powered (90 psi optimal) is the best bet. Snap-On tools has them labeled as the "Crud-Thugger". Some automotive parts houses can get them under the "Nesco" name from "Pro's Choice" for about $329. - Replacement rubber wheels for $20. ea. I got mine from "Snap-On" Tools, paid a premium, but it paid for itself in one day. Especially great for reflectives that don't have the Contro-Tac adhesive.