ASC Chevy Silverado or GMC Sierra Full Size Extended Cab Truck 1999-2006 Dual 12" Subwoofer Custom Fit Sub Box Speaker Enclosure - Armor Coated Dimensions: Width 51" x Front Height 9-3/4" x Rear Height 7-1/4" x Depth 13-1/2" Install Location: Under Rear Seat Install Notes: No Modifications Required Mounting Depth: 5-3/4 Inches Air Space: 0.95 Cubic Feet