Bosch bonded abrasive wheels are made with high-quality Aluminum Oxide grit for exceptional speed and durability in tough environments. Carefully formulated resinoid bonds are applied to meet the unique specifications of each wheel. Multiple layers of long, stranded fiberglass are woven to form an exceptionally strong reinforcement layer specific to metal, pipeline or stainless steel applications. These abrasive wheels feature 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.