From the Manufacturer:
The black SUB 8006-AS Professional Series Active Subwoofer from RCF features two 18” transducers with 4” inside/outside voice coils, designed to deliver a strong low frequency response. This direct radiating, high output, large-format subwoofer system is designed to compliment full-range loudspeakers. Driver mounting maximizes cone area and minimizes frontal area, providing acoustical performance and physical configuration well suited for creating large subwoofer arrays.
This subwoofer has been designed to extract efficiency from every part of the system, allowing for accurate low frequency transient response. As a self-powered system, the transducers, amplification, and DSP are designed to optimize performance, and maximize power.