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.? Made of Nylon with Buna-N seals. Resistant to salt water, and most mild chemicals and oils, these strain?reliefs are noncorrosive and suitable for direct-burial installations. The 1/2″ thread,?two-hole strain relief,? is rated for up to 1,000 VDC and can be used with PV Wire up to 0.27″?outside diameter. UL-listed for use in NEMA 4, 6 and 12 application.