Uxcell Speaker Sound-Absorbing Cotton Polyester Fiber Audio Interior Insulation DIY Replacement 24.41''x39.37'' White
Features:
Speaker sound-absorbing cotton is installed in the speaker to absorb standing from the low frequency of the offset. 
After installing the sound-absorbing cotton, will make the bass clearer and strong without.High-Fidelity.
The acoustic propagation will make space larger. 
The amount of sound absorption cotton in a box should be actually.
When the bass is smeared, install more sound-absorbing cotton. Otherwise, reduce cotton.
It is a sound-absorbing cotton dedicated to speakers, flame retardant

Tips: Because the cotton is soft and elastic, the cotton shape sometimes appears thin when pressed. After natural, the thickness is 3cm approximately.