Use the 1/2" NPT threaded connectors to provide a waterproof entrance or exit for wiring on PV module junction boxes and outdoor combiner boxes. Use the 3/4" NPT connector for cables up to 5/8" dia. Made of Nylon with Buna-N seals. Resistant to salt water, weak acids, weak alkalis, alcohol, ether, esters, ketones, and mineral, animal and vegetable oils. Non-corrosive, suitable for direct burial installations. The oval-hole 1/2" strain relief works for 2-conductor TC cable used for module interconnects, PV outputs or UF cable. The 2-hole 1/2" connector is designed for use with two #10 or #12 type USE conductors. UL Listed. Suitable for use in NEMA 4, 6 and 12 applications.