Extension column connectors are used in ceiling mounted installations to join two Peerless-AV extension columns (EXT or AEC). The large pass-through in the side of the connector allows cabling to enter or exit the extension column. This can be used to route cabling into the extension column at the ceiling connection or can be used to route cabling out of the extension column at the display or projector side. The set screws lock the connector in place and prevent it from unthreading.