External Pole Joiner The BT5924 is an external joiner from B-Tech’s System V Range; a collection of components designed for the installation of CCTV and other ceiling mounted equipment. Designed for use with BT5935 ø38mm poles, the joiner allows for an extended drop of System V installations, fixing over the ends of the two poles to create a rigid join. Adding compatible B-Tech mounting interfaces and accessory collars to mount CCTV dome cameras and other AV equipment such as flat screens, allows users of System V to create custom ceiling mounted solutions that suit their specific needs.