Bassforms BF212SQUARE Dual 12" Custom Fiberglass Enclosures for Square Subwoofers 2002-2015 Dual 12" Custom Fiberglass Enclosure for Square Subwoofers Constructed with 4 layers of 2oz. Matting: 100% Fiberglass Custom looks & form minimizes trunk junk: Lightest, most durable boxes on the market Designed for louder, deeper bass Airspace: 3.28 / Speaker Depth: 10.23