5-Level Multi-Surface brushes, ideal for washing cars, trucks, boats, RV’s, scrubbing floors, decks or walls and many other surfaces. There are 3 different stiffness options for this brush series. The blue nylon is the softest, which is the best choice for use on surfaces where scratching is more susceptible. The yellow polypropylene is a medium-stiff option providing some softness due to the flagged ends of the bristle but at the same time providing the required stiffness for general scrubbing. This yellow version is the closest to your all around wash brush. The last option is a red stiff polyproylene, which should not be used on cars or other vehicles as scratching is more likely to occurr. Its better suited for scrubbing floors, decks, walls or other hard surfaces where scratching is not imprtant. Although these brushes are suitable for many types of surfaces, some brushes may be suseptible to scratching, always test the brush out first whenever your unsure. The foam block also offers a flow through hole design, that can be used with a threaded flow through handle. Brushes are made right here in the U.S.A