About the Fusion MS-FR4021

Small speakers, big sound
Small speakers, big sound
Fusion's MS-FR4021 4" marine speakers pack a lot of tech into a compact design. The heat-pressed poly cones feature German "CURV" technology, which uses a woven fiber composite that's heat-pressed to form a lighter, stronger cone. When combined with titanium dome tweeters, the result is a high-performance 4" speaker that sounds great and is built to last.
Technology and value
A boat is a rough place for speakers. Heat, humidity, salt, spray, and high-pressure hose-downs at the dock can shorten the life of any speaker that's not built for life on the water. These marine speakers meet the toughest standards for UV stability and salt/fog resistance. Rigorous testing ensures that they're ready to rock, even in the extremes of a marine environment.
Three-year warranty
The water-resistant design complies with ASTM standards for UV stability and salt/fog resistance, so your MS-FR4021 speakers will perform at their peak even after prolonged exposure to the elements. As part of Fusion's True Marine™ line, they're even backed by a 3-year warranty.
Product highlights:
- 4" 2-way marine speakers (pair)
- sealed, water-resistant construction
- heat-pressed poly cones using German CURV technology
- titanium dome tweeter
- UV-resistant white grilles
- meets IP65 water and dust resistant standards
- complies with ASTM standards for UV stability (ASTM-D4329) and salt/fog resistance (ASTM-B117)
- high-efficiency design reduces battery drain
- engineered to minimize magnetic interference to navigational equipment
- power handling: 25 watts RMS (120 watts peak)
- frequency response: 90-22,000 Hz
- sensitivity: 87 dB
- cutout diameter: 3.71"
- frame diameter: 5.18"
- mounting depth: 2"
- warranty: 3 years
- Our 60-day money-back guarantee
- MFR # MS-FR4021
What's in the box:
Fusion MS-FR4021 owner's manual
- Two 2-way Marine speakers
- 2 Grilles
- 2 Foam gaskets
- Two 14-3/4' Lengths of speaker wire (each has female quick-slides on one end and bare wire on the other)
- Eight 1-1/8" Stainless steel screws
- Installation manual
- Warranty information
- Template
Reviews
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More details on the Fusion MS-FR4021

Features & specs
General | ||
---|---|---|
Speaker Size | 4 | |
Design | 2-way | |
Tweeter Design | Dome | |
Tweeter Composition | Titanium | |
Woofer Composition | Poly/Fiber Composite | |
Woofer Surround | Rubber | |
Parts Warranty | 3 Years | |
Labor Warranty | 3 Years | |
Specifications | ||
Sensitivity |
87 dB at 1 watt | |
Frequency Response | 90 - 22k Hz | |
Max RMS Power Handling | 25 | |
Peak Power Handling (Watts) | 120 | |
Impedance (Ohms) | 4 | |
Top-mount Depth (Inches) | 2 | |
Bottom-mount Depth (Inches) | N/A | |
Cutout Diameter or Length (inches) | 3 3/4 | |
Bolt Circle | --- |
Product Research
Features
True Marine: Fusion describes these speakers as True Marine Accredited, meaning they are designed specifically for the marine environment and backed by Fusion's 3 year warranty. The speakers are tested to ensure they meet or surpass IP65 (waterproof and dustproof), ASTM-D4329 (UV stability), and ASTM-B117 (salt/fog resistance) standards. The tweeter housing, crossover, and magnet are all sealed.
Curv Woofer Cone: CURV technology incorporates a polypropylene/woven fiber composite, heat pressed to form a lighter and stronger cone. This improves sound definition and increases output, along with creating better resistance to the marine environment.
Size: The MS-FR4021s fit into standard 4" openings (standard car speaker size), but the frame is bigger than a typical 4" car speaker.
Magnetic Shielding: Magnetic interference is something to take into consideration when installing marine electronics. Fusion added a bucking magnet at the rear of the speaker motor assembly to reduce interference that can occur with compasses or compass-based electronics.
Stainless Steel Hardware: The provided mounting screws are stainless steel.
Enclosure: Enclosure recommendations are given in the installation manual (an enclosure is not necessary, the speakers will operate in free-air):
- Sealed: 0.07 ft³
- Ported: 0.34 ft³ (with a 2" diameter 3-7/16" long port tube)
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Customer Q&A
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Great speakers! Good quality and very durable. They Handel high UV and salt water great! They Handel over powering well and kick out a lot of sound for small speakers
Andrew from USVI