VTLF combines several technologies to create a unique acoustical core. First, it is an exceptional 80Hz bass trap- exactly at the key woofer to subwoofer crossover frequency. Unlike a traditional bass trap, it continues to absorb up through the woofer frequencies (315 Hz) then it turns off, preserving the mid and high tones. Lastly it does this without the need for heavy materials and is only 2-1/8″ thick!