A detailing brush set typically contains 3 to 5 brushes of varying diameters. They are designed to clean the areas a wash mitt cannot reach. They come in natural boar’s hair (soft, for painted emblems) or ultra-soft synthetic fibers (for delicate piano black interior trim). They are indispensable for agitating cleaner inside AC vents, around the lug nuts, in between leather seat seams, and around badge lettering where wax often gets stuck and dries white.