• Best For: Contractors cutting concrete and masonry on a 12 inch saw with a 1 inch spindle, who want the standard-thickness MK Diamond MK-404D rather than the wide .375 inch version.
• Highlight: This is the 1 inch arbor listing of the 12 inch MK-404D; the otherwise identical part number 150403Z carries a 20mm arbor instead.
• Expert Note: Measure the spindle before ordering. MK Diamond publishes the 1 inch and 20mm bores as separate part numbers at the same list price, so picking the wrong one means an exchange rather than a bushing.