Sealcon NN-21-BR high quality nickel plated brass locking nuts are liquid tight to 150 psi. 3/4" NPT Thread. Sold Individually. Sealcon 3/4" NPT Nickel Plated Brass Locking Nuts provide a NEMA 4x & 6 (IP 68 & 69K), 150 PSIG (10 bar) Liquid Tight Rating.