The Netix 29-0025 is an inline RJ45 female-to-female coupler (joiner) for connecting two network cables end to end. It's the simplest way to extend a patch lead that's come up short - plug a CAT5 or CAT5e cable into each side and you get one longer run - or to join cables temporarily when moving a PC, printer or router. It is an 8-wire, straight-through (parallel-wired) adapter in a compact light beige housing, with an RJ45 socket on each end. Being passive, it needs no power or setup. For best results keep total cable length within the 100m Ethernet limit and avoid daisy-chaining several couplers. Esquire supplies it in a retail box with no warranty.