BassForms BF212 Dual 12" Universal Fiberglass Enclosure Dual 12" Universal Fiberglass Enclosure Constructed with 4 layers of 2oz. Matting: 100% Fiberglass Designed for louder, deeper bass Custom looks & form minimizes trunk junk: Lightest, most durable boxes on the market Airspace: 2.56 / Speaker Depth: 7.9