J.W. Winco KM-4 KM Bearing Lock Nut, M20 x 1.0 Thread, 32 mm OD, 6 mm Thickness, 4 mm Slot Width-2 mm Slot Depth (4): Amazon.com: Industrial & Scientific
Metric Bearing Lock Nuts and Washers from J.W. Winco
KM Steel Bearing Lock Nuts, Plain Finish, Flat Design | JW Winco Standard Parts