ASC Chevy Silverado or GMC Sierra Full Size Extended Cab Truck 2007-2013 Dual 12" Subwoofer Custom Fit Sub Box Speaker Enclosure Dimensions: Width 55-3/4" x Front Height 8-3/4" x Rear Height 5" x Depth 14-3/4" Install Location: Under Rear Seat Install Notes: No Modifications Required Mounting Depth: 6 Inches Air Space: 0.60 Cubic Feet