Compression Fittings: Nylon Compression Fittings (Black): These nylon junction box connectors are resistant to salt water, weak acids, weak alkalis, alcohol, esters, ketones, ether, gasoline, mineral oil, animal and vegetable oil and exceed NEMA 6 specifications for liquid tight . They can be utilized underwater to 300 feet, underground for direct burial cables, fiber optics, computers, control cabinets, instruments, medical/dental equipment, car washes, hot tubs, and carpet cleaning machines . Made of 6/6 Nylon with a flame resistant self extinguishing, Buna-N seal . Black . Comes complete with lock-nut .