JBL SRX910LA BP Base PlateThe SRX910LA Base Plate is a universal adapter frame that enables SRX910LA arrays to be ground stacked on top of compatible subwoofers or support structures such as stages, scaffolding, or carts. Using the included M20 screw, the SRX910LA BP connects to any supported subwoofer equipped with a standard M20 pole mount adapter, such as the SRX928S. The rear angle selection bar allows for angles ranging from 15 to +5 degrees. The three included M10