Wheel Woolie Medium WWMED18 18" Automotive Wheel Cleaning Brush Medium Wheel Woolies are perfectly sized for small gaps, air diffusers, door jams and an endless number of places in the engine bay. Completely metal free and will not scratch. Made of polyproylene, these brushes will not scratch up or splatter like most twisted wire spoke brushes. The soft, dense carpet fibers will hold suds and transfer them to the wheel. Made in the USA.