What is that cloth you pit in a sub?

[Terranova 10+ year member]

i am curious as well, im contemplating on putting this stuff in my next ported box. should i do it lol?

 

[Rashaddd 5,000+ posts]

http://www.moodym.com/audio/fiber.html

looks like for ported boxes even higher density, but again depends on enclosure size to begin with

 

[snoopdan 5,000+ posts]

i am curious as well, im contemplating on putting this stuff in my next ported box. should i do it lol?

Well that depends, are you wanting it to effect tuning? Because thats what it will do. The surface area/thermal load effect only works when put it in a sealed enclosure.