The HDX Plumbing Brushes are perfect for prepping and cleaning your pipe and fittings. The HDX 1/2 in. x 3 in. Acid Brush and 3-Piece Acid Brushes are designed for use when applying paste fluxes to piping prior to soldering while the HDX Tube Cleaning Brushes smooth the outside of plastic or metal pipes for easier soldering. The HDX Heavy-Duty Fitting Brushes clean the inside of the inside of copper, brass or plastic fittings prior to soldering.