The The KickPort® Patented design enhances the sound of your kick drum by doing four things:It ports the kick drum in the same manner as a bass reflex speaker cabinet which boosts low frequencies.It adds ideal dampening directly to the resonant head which allows you to remove most if not all of the internal materials thus reclaiming all of the natural resonance and tone of your drum.It focuses the air as it exits the kick drum and this compression increases punch. It';s tunable!; Due to its broadband design, The KickPort® improves;the sound of bass drums sized 16"; to ;28.", It can be tuned up or down by adjusting the tuning of the resonant head.; The overall result is more lows, more tone, better definition and more punch in varying acoustical environments.; Additionally these are benefits the drummer can feel behind the kit.