Fusion MS-FR4021 4 Inch Marine Speaker Spacer Ring Adapters – Custom King Starboard Depth Extension Pair

Solve tight installation challenges across your boat using Fusion MS-FR4021 4 inch marine speaker spacer ring adapters. Specially crafted for 4-inch Fusion MS-FR4021 drivers, these extension plates offset speaker baskets to prevent drivers from bottoming out against internal bulkheads or wiring harnesses.

USA-manufactured from high-density King Starboard marine sheet, each pair resists severe weather, UV breakdown, and constant salt spray exposure without peeling or absorbing water. Mounting these sturdy rings yields a secure, flush seal across hull walls and console panels, improving mid-range clarity while shielding fiberglass surfaces from strain.

Key Features

• Direct Fusion 4″ Driver Fit: Tailored dimensions mirror the exact frame profile and bolt-hole spacing of Fusion MS-FR4021 drivers.

• USA-Made King Starboard Construction: Solid, high-density polymer guaranteed against rotting, swelling, or water degradation.

• Creates Crucial Back-Spacing: Relieves shallow cutout restrictions to protect delicate rear magnets and wiring runs.

• Resonance Reduction: Heavy-duty baffle dampens structural panel buzz for cleaner, punchier sound delivery.

• Clean Marine Finish: Features smooth rounded edges in OEM white or black to match existing helm trim.

Engineered Frame Compatibility

Designed specifically around the footprint of Fusion MS-FR4021 4-inch marine speakers, these adapters require no extra cutting or retrofitting. The inner diameter cradles the basket seamlessly. This tight physical fit creates a dependable seal that keeps sound energy focused outward.

Heavy-Duty Weatherproofing

Constructed from genuine marine-grade King Starboard, these rings thrive in active ocean conditions. Unlike standard plastics or marine plywood, this polymer withstands intense sunlight and continuous saltwater spray. It maintains structural integrity season after season.

Clears Restrictive Hull Depths

Mounting compact speakers in tight helm consoles often leads to clearance problems behind the panel. These spacer plates shift the speaker frame forward into open cabin space. This simple clearance boost prevents internal impacts and extends equipment life.

Solid Baffle Performance

Thin fiberglass sections often vibrate when speakers run at high volume levels. These solid 1/2-inch Starboard spacers reinforce the surrounding panel area. They absorb mechanical shake, reduce rattle, and deliver crisp sound reproduction.

Upgrade Your Marine Audio Today

Eliminate shallow cutout headaches and protect your audio gear today. Order your Fusion MS-FR4021 4 inch marine speaker ring adapters now for exact component alignment, total weather durability, and a polished marine look.

Fusion MS FR4021 (Pair) 4″ Marine Boat Speaker Spacer Rings King Starboard

Don’t have enough depth to install your speaker/subwoofer? Problem solved these spacer rings give you that extra space needed to mount your speaker/subwoofer.

What your getting and how to order

Frame Outer Diameter 5.375″
Bolt Hole Circle Diameter ( 4) 4.625″
Mounting Hole Diameter 3.875″

-Select your thickness 1/4″,1/2″,3/4″ or 1″
-Select your edge profile (Straight, 1/8 Round, 1/4 Round)
-These are made with the best Starboard on the market King Plastics not that other cheap stuff
-We have been working with King Starboard for a very long time and we take pride in what we do

Don’t see a size you need?
Contact us and we would be more then happy to get you what you need, we make spacers for all brands and sizes.