Metabo 341101480 5/8-11 Flange nut, used on 5/8-11 spindles to support 7/8" wheels or other wheels - Tool Authority
Set of 5 Grinder Flange Replacement Parts 5/8-11 Grinder Nuts with Spanner Wrench, Angle Grinder Attachments Compatible with Dewalt Milwaukee Ryobi Makita - Amazon.com