XLR connectors are three conductor plugs and jacks used in professional grade microphone and similar audio equipment. They are easy to apply, but do require soldering. Each piece has a silver metal barrel, rubber strain relief, plastic core with conductors, and a small Philips screw that holds core to barrel (note that this screw is remarkably easy to lose!). Useful as a replacement part, or to turn an existing contiguous two- or three-conductor cord into a detachable cord. Male connector has pins that go in, female connector has holes that receive pins. Pins on each side are numbered 1, 2, and 3. OA machines use connection of Black = 1, White = 2, and Green = 3. Also available for builders is a female XLR panel jack, which secures into a 7/8″ hole with two small screws.