10-1.50mm Screw Size 15mm Hex Size 21mm O.D. Washer Black Finish Metric Hex Flange Nuts Compare with: Auveco #11645, G.M. # 11501850, Car Pak # 76-4411, 764411, Disco # 1017PK, 1017B, W&E #5909, Barnes / Kar # MP1488, 1488, Kent / Lawson # P35102, Winzer # 395.402, Crest / Midwest # CRX696, S&R # 236090