The SRX910LA Base Plate allows stacking of up to 4 SRX910LA speaker arrays onto subwoofers and other ground-based support structures. The plate’s angle range of -15 degrees to +5 degrees lets you position the arrays for optimum sound dispersion in any venue. The SRX910LA Base Plate works with any supported subwoofer bearing a standard M20 pole-mount adapter, and you can also use the included M10 through-holes to permanently install a SRX910LA array to other structures.