This a custom built sealed enclosure built to Polk audio specs. Basically the guys at my local car stereo shop told me there's no way to build a sealed enclosure to replace the factory Rockford fosgate 8 in. So just to prove it could be done I built this. If you want some real, hard hitting bass in a spyder, this box is the only way to go. Does not interfere with the storage area for the convertible top. No cutting or chopping of the car required! Fits any Spyder from 2007-2012 the sub is a Polk audio Momo MM1040