These nylon brushes retain their shape and do not rust. Do not shed bristles under normal conditions. Material: Composite nylon abrasive sand. So the nylon bristle brush is safe to use than steel wire brushes and will not pierce the skin. Applications: Removing paint, corrosion, surface weld, rust and burns from metals. Can also be used for polishing and deburring wood. These nylon brushes with 1/4" shank fit most drills. RPM: 4500 RPM - 3 different grits to meet different sanding needs. Package Included: 1 x Red Cup Brush 80#, 1 x Gray Cup Brush 120#, 1 x Blue Cup Brush-320#; 1/4" Round Shank, Max. RPM: 4500 RPM. Specifications: Material: Composite nylon sanding sand. Size: 3" Wheel; 1/4" Shank; Maximum 4500 RPM. Package Contents: 1 x Red 80#, 1 x Gray 120#, 1 x Blue 320#; 3pcs in total. Features: Retains its shape and does not rust, does not shed under normal conditions. Safer to use, does not penetrate the skin. Safe to use as wire brushes. Applications: Removing paint, corrosion, surface welding, rust and burns from metals. Cleaning tiles, stones, cement and bricks. Removing old paint and surfaces from wood. Cleaning and sanding wood chips, railings, moldings and trim. Note: 1. Due to the different monitor and light effect, the actual color of the item might be slightly different from the color showed on the pictures. 2. Since the size above is measured by hand, the size of the actual item you received could be slightly different from the size above. Please do not disturb, thank you. Quantity delivered: 3 pieces. Welcome to meet