No one has as much experience designing and building subwoofer enclosures as JBL. Our speaker enclosures have travelled thousands of miles, touring with some of the world's top bands and have filled stadiums, auditoriums and local clubs with rockin' bass for half a century. Our car audio subwoofer enclosures are built to the same exacting standards as our professional boxes and are designed to be rugged and to sound great. GTO enclosures feature 3/4" medium density fiberboard (MDF) construction, high-quality binding post terminals and GTO woofers. GTO enclosures are available in single or dual bandpass configurations. Unlike so many one-note-wonder enclosed subwoofers, GTO enclosures feature wide bandwidth design, which provides more output between 20Hz and 40Hz and ensures you get all the bass you've paid for.