5/16"-18 Serrated Flange Lock Nut - Plated 5/16"-18 serrated flange lock nut - plated SFN51618 $0.057/ea
5/8"-11 Serrated Flange Lock Nut - Plated 5/8"-11 serrated flange lock nut - plated SFN5811 $0.540/ea