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.