No special tools needed. Rubber coupling which sits on motor base and drivers the blender blades. Original part number: 9704230 Works with models: KSB3WH0, KSB3AC0, 4KSB5WH0, KSB3, KSB3WH, KSB5, KSB5WH, KSB3-4, KSB5-4, 5KSB5-4, KSB5SS-4, 5KSB52-4, KSB5, KSB3-3, KSB5-3.
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