Sealcon NM-40-SS high quality stainless steel locking nuts are liquid tight to 150 psi. M40 x 1.5 Metric Thread. Sold Individually. Made from 303 stainless steel. Sealcon M40 x 1.5 Stainless Steel Locking Nuts provide a NEMA 4x & 6 (IP 68 & 69K), 150 PSIG (10 bar) Liquid Tight Rating. Some common uses include chemical plants, off shore rigs, food processing and marine applications.