The Apart CMBB is a back-box for the Apart build-in speakers CM6T, CM6E, CM20T and CM608.Due to the conical shape, the CMBB will perfectly fit and stick into a concrete or brick wall. The CMBB can alos be used as an on-wall back-box.Mounting the CMBB is very easy! First the base is mounted on the wall or ceiling. Then the back-box can be fitted on the base plate by turning the ring counter-clockwise. The ring can be secured by 3 included screws. Afterwards the loudspeaker can be mounted into the back-box.