RT/OBCON - 1998 Chevy Silverado and GM Sierra 1500 Extended Cab Single 12" Speaker Box With Labyrinth Power Port Designed for: 1998 Chevy Silverado 1500 and GM Sierra 1500 28 1/2" width x 15 1/8" deep x 9 1/2" tall Premium 5/8" MDF with "Tri-lock" joint construction Speaker mounting depth: 5 3/4" - Air Volume: 1.2cf Single 12" Labyrinth slot vented enclosure design (downfire)