Measure inside edge to inside edge along the longer dimension of the duct opening.
Linear Slot Diffusers
Aluminum linear slot diffusers for ceilings, walls and floors. Find your duct opening size — length × width and compare dimensions and airflow to choose the right fit.
6–84" lengths
2–24" duct opening widths
Aluminum construction
Find Your Size
Either dimension order works
Duct opening size
View Product
Not a standard size
Enter the two duct-opening dimensions in either order. 6 × 12 and 12 × 6 match the same product.
256standard sizes
6–84"available lengths
2–24"duct opening widths
Aluminumconstruction
Browse the catalog
Browse by duct opening width.
Select the duct opening width, then choose the required length. Airvian uses 1-inch slots; slot quantity increases with width from 1 slot at 2 inches to 12 slots at 24 inches.
2" Duct Width
1 Slot · 1" Slot Width
Available lengths from 6"
4" Duct Width
2 Slots · 1" Slot Width
Available lengths from 6"
6" Duct Width
3 Slots · 1" Slot Width
Available lengths from 6"
8" Duct Width
4 Slots · 1" Slot Width
Available lengths from 8"
10" Duct Width
5 Slots · 1" Slot Width
Available lengths from 10"
12" Duct Width
6 Slots · 1" Slot Width
Available lengths from 12"
14" Duct Width
7 Slots · 1" Slot Width
Available lengths from 14"
16" Duct Width
8 Slots · 1" Slot Width
Available lengths from 16"
18" Duct Width
9 Slots · 1" Slot Width
Available lengths from 18"
20" Duct Width
10 Slots · 1" Slot Width
Available lengths from 20"
22" Duct Width
11 Slots · 1" Slot Width
Available lengths from 22"
24" Duct Width
12 Slots · 1" Slot Width
Available lengths from 24"
Choose the right size
Measure the duct opening: length × width.
Both dimensions matter. Measure the inside opening first; the duct opening width determines the slot quantity.
Measure the inside width. In the Airvian range, duct opening width ÷ 2 = slot quantity.
Compare the neck and face dimensions with your opening, then check the listed airflow in CFM.
12 × 6 Example
See the size, dimensions and airflow before you order.
For a 12 × 6 diffuser, 12 × 6 is the duct opening size. The 6-inch width uses three 1-inch slots. Compare the neck size, visible face size and rated airflow below to check the fit for your opening.
Duct opening size12 × 6 in
Slot quantity3 slots
Slot width1 in
ConstructionAluminum
Neck size11 7/8 in × 5 13/16 in
Face size14 1/8 in × 7 7/16 in
Rated airflow151 CFM
Effective velocity550 FPM
Airflow controlAdjustable internal airflow wings
Measure before you order
Measure the duct opening, not the old vent face.
The nominal product size refers to the inside duct opening. Measure both the length and width before selecting a diffuser.
Measure inside length
Measure inside width
Width determines slot count
Verify neck and visible face dimensions
View the Measuring Guide
Applications
For ceilings, walls and floors.
Find the right size for your ceiling, wall or floor opening. Measure the inside length and width, then check the space behind the opening and how the diffuser will be secured.
Ceiling Applications
Linear air distribution for finished ceilings, soffits and overhead HVAC layouts.
Wall Applications
A clean architectural outlet where the diffuser becomes part of the finished wall design.
Floor Applications
Air distribution from floor-level openings, with space for the diffuser neck and secure mounting support.
Guides
Guides for sizing and selection.
01How to Measure
Measure the inside length and width of the duct opening before choosing a size.
Read guide → 02What Is a Linear Slot Diffuser?Understand duct opening size, slot quantity, slot width, neck dimensions and face size.
Read guide → 03Supply Air vs. Return AirUnderstand the different jobs of supply outlets and return inlets in an HVAC system.
Read guide →Frequently asked questions
Linear slot diffuser sizing questions.
Start with the duct opening dimensions. Slot count follows the width.
What does a size like 24 × 4 mean?+
It means a nominal duct opening 24 inches long × 4 inches wide. The product page lists the exact neck and visible face dimensions separately.
How is slot count determined?+
Slot count follows nominal width. In the Airvian range, every 2 inches of nominal width equals one slot: 2" = 1 slot, 4" = 2 slots, 8" = 4 slots, through 24" = 12 slots.
Which dimensions should I measure?+
Measure both inside dimensions of the duct opening. You can enter them in either order; Airvian will match the same rectangular opening.
Is 6 × 12 the same as 12 × 6?+
Yes. Both sizes describe the same rectangular duct opening. Enter either 6 × 12 or 12 × 6 in the size finder to find the same diffuser.
Do the neck and visible face differ from the nominal size?+
Yes. The nominal size refers to the duct opening. Exact neck and visible face dimensions are shown on every Airvian product page.
Is airflow information provided?+
Yes. Each product includes rated CFM and an effective velocity reference of 550 FPM alongside its dimensions.
Can Airvian linear slot diffusers be used in ceilings, walls and floors?+
Airvian linear slot diffusers are available for ceiling, wall and floor applications. Check the neck and face dimensions, mounting support and space behind your opening to choose the right fit.
Find your size
Find your diffuser by duct opening size.
Choose your duct opening length and width to find your Airvian diffuser.