The Bosch 3" Wheel Diameter X-LOCK Arbor Stainless Steel Knotted Wire Single Row Cup Brush (WBX329) features the X-LOCK mount that offers a change out that's up to five times faster than conventional interfaces. There’s an audible snap when mounting an X-LOCK wheel on an X-LOCK grinder. The wheel mounts properly without the need for a spanner wrench or flange nuts. The wheel is released from the grinder with the pull of a lever. Bosch Cup Brushes are ideal for removing weld scale, burrs, and corrosion. These crimped wire cup brushes are made with carbon steel bristles that provide a softer brushing action for confined spaces. The precision-balanced cup virtually eliminates vibration and they are made with high-quality materials. X-LOCK Cup Brushes are not backward compatible with standard 7/8 In. mounts.