3/8"-16 Serrated Flange Lock Nut - Plated 3/8"-16 serrated flange lock nut - plated SFN3816 $0.084/ea
5/16"-24 Serrated Flange Lock Nut - Plated 5/16"-24 serrated flange lock nut - plated SFN51624 $0.087/ea