Arrays can be assembled using only WLA-25 line array elements or with WLA-25SUB Subwoofers at the top of the array. The WLA-25SUB Fly Frame allows for a WLA-25SUB or WLA-25SUB MKII subwoofer to be used at the top of the array. It supports up to 12 x WLA-25 elements and 1 x WLA-25SUB / SUB MKII with a safety factor of 12.