compatible with chevy silverado or gmc sierra full size extended cab truck 2007-2013 dual 12" subwoofer sub box speaker enclosure american sound connection we finally have a custom fit enclosure available for the new body style chevy 07-12 silverado / gmc sierra extended cab truck! this dual 12" enclosure is designed to fit under the rear bench seat and is a down firing model. why down firing? not only does it help improve the overall spl output of the subwoofers but it also keeps the subs out of view for security reasons. this enclosure is compatible with a wide range of sub brands and model but entry level and flat piston subwoofers tend to work best. our boxes are made from precision cuts of mdf. they are then liquid nailed, nailed and completely sealed. we then wrap them with high quality carpet that matches most vehicle interiors. all boxes feature high grade spring loaded terminal cup(s) for the absolute best connection possible. all the custom series enclosures are made to fit precisely into your 07-12 chevy silverado extended cab to the get the max performance from every extra inch of wasted space. we guarantee you will not only see a difference in the quality of the boxes we build, but you will hear the difference and that is what is it is truly all about.