The M225 is a bass reflex, down firing 8" woofer design, with a forward firing bass vent. This is a seriously designed subwoofer with custom tuned crossover circuitry to provide a perfectly seamless blend between the sub and the MS satellite speaker. The critical factor in a good sounding sub-sat speaker system is the output frequencies of the subwoofer. The athena engineers utilized our SCT system, and have custom tuned the subwoofer in our anechoic measurement facilities to ensure perfect results. The biggest benefit is the set up is easier than ever, due to the sub having fewer controls to set. Simply connect and adjust the volume. A sonic blend between the subwoofer and MS speaker is guaranteed!