Box Insulation?

[Scuba]

Is there anything good I can use to insolate my sub box other then the pink Insulation you use for your house? Maybe those blue shop towels you buy from partstores? Just like paper towel. Or how about cotton? Rags? My box is just slightly to small to the specs for my sub and i heard this would help the way it sounds.

Thanks

[Wagonized]

polyfill is what most people use...available at walmart or any fabric store. The shit you put inside pillows