Bristle Brushes are used to clean and prepare surfaces for buffing and polishing. Bristle Brushes are used to clean and prepare flat, curved, and uneven surfaces for buffing and polishing and to polish with polishing compounds. They are made with natural bristles–chunking for stiff, horsehair for firm, and goat hair for soft bristles. 3/32″ (2.35 mm) shanks. Steel rings hold and evenly distribute bristles. 25,000 Maximum RPMs.