The Shure A900-CM Ceiling Mount allows Shure ceiling array microphones to be mounted to a drywall/joist, plywood/joist, or concrete ceiling, or a 4-inch octagon junction box. Its two-piece design makes installation straightforward. The included ceiling plate attaches to a joist, the concrete ceiling, or a junction box. The ceiling adaptor plate attaches to the top of the microphone. The two plates then slide together and are secured by a hex screw. Compatible with MXA902, MXA910, and square and round MXA920 ceiling array microphones.