Fastening type

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  Round hole fastening type describes the central hole in a sanding disc, cutoff wheel, or similar, where the tool's arbor goes through the hole in the disc or wheel and is held on by a pair of washers and a nut. Depending on the item held onto the tool by a round hole, there may be a backing pad that also has a central round hole.

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  Round shank fastening type indicates a disc or wheel which comes from the manufacturer mounted on a round shank.

• Threaded Shank fastening type is a disc with a male-threaded shank that twists to connect to a power tool.