8+ 18 Inch Sub Box. Net internal volume 6.00 cubic feet. The tx18s is designed for superior bass output, delivering deep, clear, and controlled low frequencies that enhance any audio setup.

Net internal volume 5.83 cubic feet, port area 85.24 square inches, tuning frequency 36 hz. Featuring the most bass from one box in the industry, the seismic audio quad 18 revolutionizes low end at an affordable price. Net internal volume 6.00 cubic feet.