3/8 Lead-Free Bulkhead Union with LocknutThe 3 8 Compression x 3 8 Compression Lead Free Bulkhead Union with Locknut is a compression union designed to securely connect two pieces of tubing or pipe, each with an outer diameter. A bulkhead union is a fitting that allows for a connection to be made through a wall or barrier, often used to create a seal through a container or panel. The locknut provides extra security, ensuring that the fitting stays securely in place even under pressure.