About the MTX ThunderForm Unloaded Enclosure
Crinkled french fries, discarded receipts, old gum wrappers you probably have everything in the hidden corners of your vehicle except great bass. ThunderForm enclosures fill the nooks and crannies of your vehicle with low tones that stand out, but their factory look blends right in.
MTX engineers evaluate the "sonic signatures" of top-selling vehicles so they can design ThunderForms as custom acoustic matches. Each ThunderForm fits and blends inconspicuously into your vehicle, so you get great bass without losing any space. They're made of high-density polyethylene resin to curb resonances they deliver bass that's tight, hard-hitting, and way down low. The airtight enclosure provides the correct internal volume to yield optimum bass response.
This enclosure comes without a speaker you install your favorite 12" subwoofer. For best results, MTX strongly recommends using a speaker designed for an enclosure with a volume of 1.25 cubic feet. The enclosure mounts behind the rear seat on driver's side of the hatch in select 2009-up Ford Focus ZX3 or ZX5 models.
Please check with us before purchasing by using the vehicle selector on our site, or calling an Advisor at 1-888-955-6000 to verify fit information.
Product highlights:
- custom-fit charcoal subwoofer enclosure for 12" sub
- mounts behind rear seat on driver's side of hatch
- fiberglass construction
- volume: 1.25 cubic feet (sealed)
- dimensions: 29-1/2"H x 20-1/2"W x 10"D
- mounting depth: 6-7/8"
- warranty: 2 years
- Our 60-day money-back guarantee
- MFR # FZX3500C12U
What's in the box:
MTX ThunderForm Unloaded Enclosure owner's manual
- Custom-fit unloaded 12" subwoofer enclosure
- Hardware
- Installation instructions
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More details on the MTX ThunderForm Unloaded Enclosure

Features & specs
General | ||
---|---|---|
Box Type | Sealed | |
Number of Boxes | 1 | |
Number of Speakers Per Box | 1 | |
Speaker Size | 12 | |
Cutout Diameter or Length (inches) | 11 1/8 | |
Maximum Speaker Depth (inches) | 6-7/8 | |
Box Volume (cubic feet) | 1.15 | |
Tuning Frequency | N/A | |
Height (inches) | 29-1/2 | |
Width (inches) | 20-1/2 | |
Depth (inches) | 10 | |
Second Depth (inches) | 10 | |
Wood Thickness (inches) | 0 | |
Speaker Wire Connectors | Spring posts | |
Box Color | Charcoal | |
Box Finish | Fiberglass | |
Parts Warranty | 2 Years | |
Labor Warranty | 2 Years |
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Features
Vehicle Compatibility: This Bass Slammer custom-fit enclosure is designed specifically to fit the 2000-2007 Ford Focus (XZ5 & ZX3).
Note: Please refer to the Crutchfield Vehicle Selector to confirm fit for your vehicle.
Mounting Location: The enclosure mounts in the rear drivers side, behind the back-seat firing to the side of the Ford Focus hatchback. Your vehicle's spare tire will still be accessible.
Enclosure Type: The sealed enclosure features fiberglass construction and fits one 12" woofer.
Tools For Installation:
- Powered screwdriver
- #2 Phillips head bit
- 6" Bit holder extension
- Wire cutters
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