Custom-Sized AAF Flanders PrePleat Air Filter – MERV 11 (M11) Efficiency

Description

This is our custom-size AAF Flanders PREpleat M11 air filter, delivering MERV 11 filtration built to your exact dimensions. When your HVAC system has a non-standard filter opening — common in older homes, commercial rooftop units, and legacy air handlers — stock nominal sizes leave gaps that let unfiltered air bypass the filter. Custom sizing closes that gap so your system actually filters the air it handles.

When a custom size is the right call

• Legacy air handlers with non-standard filter openings
• Commercial rooftop units with manufacturer-specific filter slots
• Older residential returns that don’t match today’s nominal sizes
• Replacement for a filter you’ve been trimming or stacking to fit
• Built-in filter housings where the equipment was designed around the filter

The PREpleat M11 is a meaningful efficiency upgrade over standard MERV 8 filters — capturing roughly 60–65% of particles in the 1–3 micron range versus the 20–30% typical of MERV 8 — at roughly the same airflow resistance.

How to order

Measure your existing filter (not the housing it sits in — filters are typically slightly smaller than the housing for installation clearance) to the nearest 1/8 inch in length, width, and depth. If you’re unsure about measurements or which filter spec is right for your system, contact us with a photo of your existing filter or housing and we’ll confirm before production. Our Filter Fit Guarantee means if you measure wrong, we’ll remake the filter at no additional cost.

What MERV 11 captures

Fine dust, pollen, pet dander, mold spores, smoke particles, and smaller allergens. MERV 11 is the standard recommendation for households with allergies, asthma, or pets, and is commonly specified for commercial office spaces where indoor air quality is a priority. Confirm your system can handle the slight increase in static pressure compared to MERV 8.

Construction

• Media: Progressive-density bi-component synthetic fibers. Mechanical capture — performance does not fade as the filter ages.
• Frame: Moisture-resistant beverage-board with diagonal support members and diamond-shaped expanded-metal media support bonded to the downstream side.
• Max operating temperature: 180°F (82°C)
• Sizing tolerance: Built to 1/8 inch increments

Typical applications

Commercial and residential HVAC where MERV 11 filtration is specified. Drop-in replacement for front-access holding frames and side-access housings.

Also worth considering

Shopping on price? Our house brand PrimeShield Advanced (MERV 11) covers the same efficiency tier across common residential and commercial sizes and is usually the better value. Choose this branded option when your equipment spec sheet or facilities team calls for it specifically.

Questions on fit, quantity, or a commercial quote?

Need a size that isn’t listed, a different pack count, or a quote for a commercial order? Get in touch — we handle facilities and commercial orders daily and can usually match or beat distributor pricing.

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