Collection: 4x12 Modern Vent Covers

A 4x12 vent cover from Green Vent is a linear slot diffuser, not a louvered floor register — it's the modern, minimal-slot alternative for a 4"×12" wall, ceiling, or floor supply duct opening. If you're picturing a traditional wood or cast-iron floor register with adjustable blades, this isn't that product; it's a flush, architectural cover with a clean slot face.

You'll see this size written as both 4x12 and 12x4 — same duct opening, just a different order. Below: what this diffuser actually is, how to confirm your size, and the specs before you buy.

What Is This 4x12 Vent Cover?

This 4x12 vent cover is a linear slot diffuser — a narrow-slot aluminum cover built for a 4"×12" supply duct opening, not a decorative louvered register. The distinction matters: a traditional floor register has adjustable blades or a damper you tilt by hand, while a linear slot diffuser has a fixed slot pattern with an internal adjustable airflow bar, giving it a flatter, more architectural look on the wall, ceiling, or floor.

Green Vent's 4x12 diffuser fits a duct opening measuring 4 inches by 12 inches, whether you see it listed as 4x12 or 12x4 — retailers write the dimensions in either order for the same size.

Duct Size vs. Face Size

Measure your duct opening — not the old cover's faceplate. The duct opening is the actual hole, not the visible face of your current register.

The 4x12 Aluminum Linear Slot Diffuser

Green Vent's 4x12 diffuser is built from powder-coated aluminum with a 2-slot face, available in White and Black. It's rated for wall and ceiling supply air, and works in low-traffic floor locations as well.

• Material: Aluminum — rust-resistant, lightweight
• Colors: White, Black
• Slot configuration: 2-Slot
• Placement: Wall, ceiling, or low-traffic floor
• Airflow: Adjustable — direct air left, right, both directions, or close it down
• Installation: Drop-in surface-mount replacement over your existing duct opening; no drywall, flooring, or duct modification required

The finish holds up without repainting or corrosion in normal residential use, and the slot face pairs with white trim, painted walls, or light wood floors without standing out as an HVAC part.

Frequently Asked Questions

Is This a Floor Register?

No — it's a linear slot diffuser, not a traditional louvered floor register. If you're looking for a floor register with adjustable blades in a wood, cast-iron, or brushed-nickel finish, this isn't that product. Green Vent's 4x12 diffuser has a fixed slot face with an internal adjustable airflow bar instead of external louvers.

Do I Need a Plenum Box?

No — this diffuser is a drop-in surface-mount replacement for your existing duct opening. It doesn't require a separate plenum box, drywall work, or duct modification; it mounts directly over the opening you already have.

Can I Install This on a Wall or Ceiling?

Yes, it's the same product for either location. The 4x12 diffuser is rated for wall, ceiling, and low-traffic floor supply air, so you don't need a different version depending on where you're installing it.

Is This Single-Slot or Double-Slot?

Green Vent's 4x12 diffuser is a 2-slot design — it's the only slot configuration available at this size. There's no single-slot version to choose between at 4x12.

Is This for Supply Air or Return Air?

Supply air only. This diffuser pushes conditioned air into the room; it isn't built for return air. If you need a return grille instead, see Green Vent's return air grilles.

Ready to replace a mismatched or dated 4x12 vent? Upgrade Your Vent — check your duct opening against the chart above and pick White or Black below.