KickPorts designs have become an industry standard for natural acoustical enhancement of drums and percussion instruments in all genres of music.Both for the audience and players, the award-winning patented KickPort delivers audible improvements to maximize the sound properties and tonal qualities like no other products or devices in the world. Sound matters!_ Fits a 4.50" to 5.25" bass drum hole__ Gives you more low end, tone and punch__ Easily installs in minutes__ Spectrum analysis of a bass drum strike shows that it enhances lower frequencies for a deeper, fatter, warmer and cleaner sound__ Reusable__ 4 inches in diameter_