New 6in Bench Grinder 1/2-20 Arbor Nut Set (Baldor XY5020A12SP & XY5020A62SP)
These are zinc-plated, grade 5 nuts (left-hand and right-hand) that hold the grinding wheels onto the ends of the armature assembly. See Baldor catalogue snippet. This is commonly used on 6in Baldor bench grinders (610, 612, 612E, 612RE, 662, 662E, 662RE, 632, 632E, 632RE, 623, 623E, 623RE).