tv receivers, tv projectors, video recorders, video recorder heads, closed circuit television cameras, camera lenses, camcorders, monitors, connection cords, extension cables, remote-control cords, video cameras, video camera tripods, audio and video camera power-supply units, sync generators, sync extenders, video distributors, video booster, switchers, cable compensator, computers, controllers, interphone, video interphone, intercom and telephone inferface