Check the listing for details. 4pcs Cast Pipe Fitting Hex Locknut with Washer NPT 1/2", 0.91" OD. Condition: New. Listed at 12.37 USD. Description:Enhanced Quality: The hex locknut is quality 304 stainless steel. It is designed with a hexagonal shape for easy tightening and loosening using a wrench. The locknut also has an O-ring groove that allows for a secure and leak-resistant connection.Practical Designed to Connect: The locknut provides a secure and reliable connection in pipe fittings with PT threads for creating tighter seals than straight threads. It helps prevent leakage and ensures the stability of the threaded connection.Easy to Use: We have given you plastic washers to facilitate your installation. To use this locknut, thread it and the washer onto the corresponding male PT threaded pipe or fitting. Use a wrench to tighten them securely against the mating surface. Ensure proper alignment and threading engagement for optimal performance and sealing.