The Bosch 4-1/2" x .045" X-LOCK Arbor Type 27A (ISO 42) 60 Grit Fast Metal/Stainless Cutting Abrasive Wheel (TCWX27S450) features the X-LOCK mount, offering a wheel change 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 bonded abrasive wheels are made with high-quality Aluminum Oxide grit for exceptional speed and durability in tough environments for cutting applications.