King Arthur’s Tools universal hex nuts are specially made to secure tandem combinations and any style Galahad or holey Galahad, especially the round profiles, to angle grinders. The new design includes a recess in the flat base which seats over any protruding arbor and securely tightens the accessory. It can be used to secure any other type of accessory and is much easier to tighten using a 13/16 inch or 21 millimeter wrench, crescent or spanner. Design includes universal hexagonal heads with a flat base. A universal nut allows 2 blades to be tandem mounted on 4 1/2 inch (115 millimeter) or 5 inch (125 millimeter) angle grinders.