5/16"-18 Serrated Flange Lock Nut - Plated 5/16"-18 serrated flange lock nut - plated SFN51618 $0.057/ea
3/8"-24 Serrated Flange Lock Nut - Plated 3/8"-24 serrated flange lock nut - plated SFN3824 $0.129/ea