An auxiliary mounting device 10 for an in ceiling speaker system comprises a ceiling reinforcing element 11 and an elongate element 21. The ceiling reinforcing element 11 includes a flat plate portion 12 and a vertical portion 14 provided to extend vertically from the flat plate portion, 12. The vertical portion 14 is capable of being in a slidable state in which the vertical portion 14 is vertically slidable and in a fixed state in which the vertical portion 14 is fixed so as not to vertically displace.