Brass plated steel wire for an effective clean. Wheel, cup & end brush assortment. 6.25mm (1/4 inch) shaft. Maximum 4500 RPM. Contents: 1 x 25mm (1) wheel brush. 1 x 50mm (2) wheel brush. 1 x 63mm (2.5) wheel brush. 1 x 100mm (4) wheel brush. 1 x 75mm (3) cup brush. 1 x 25mm (1) end brush.