Hillman Metric Carbon Brushes conduct current between stationary wires and moving parts, most commonly in a rotating shaft. Commonly used in electric motors, alternators, and electric generators and made of high-quality graphite and copper materials. Material offers strong resistance to rust and corrosion. Use as replacement parts for both the Hitachi and Ryobi brand power tools. measure 7.5mm x 6.5mm x 15mm.