Recommended RPM: 350rpm to 700rpm. All brushes have a 1/4"hex shaped quick disconnect shank. No tools needed to switch the brushes. Set includes following sizes: 1/2", 3/4", and 7/8". Flexible filaments with a silicon carbide material are engineered to provide the correct pressure to create an ideal hone. Great polishing tool which provides excellent results when used for deburring and edge reducing. Great for a wide variety of automotive, hydraulic, valve, pipe and tube applications. The brushes have a sturdy, self-centering stem.