Custom-Sized Flanders EZ Flow Fiberglass Air Filter – MERV 1–4, Disposable

Description

This is our custom-size Flanders EZ Flow Fiberglass air filter, delivering MERV 1-4 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

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.

Understanding the MERV 1–4 rating

Fiberglass media is rated MERV 1 when clean and builds up to MERV 4 as dust loads onto the fibers. That’s not inconsistency — it’s how spun-glass media works. A fresh filter lets the most air through while still blocking larger debris; as dust collects, the media becomes more efficient at catching finer particles. The goal of a MERV 1–4 filter isn’t air quality — it’s equipment protection with maximum airflow. It keeps lint, hair, and large dust out of your coil and blower, which is exactly what older systems, high-airflow applications, and pre-filter duty need.

Construction

• Media: Continuous-filament spun fiberglass bonded with resinous adhesive. Rated MERV 1 clean and builds up to MERV 4 as the filter loads.
• Frame: One-piece heavy chipboard, moisture-resistant. Media adhered directly to the frame with hot-melt adhesive, no metal retainer.
• Max operating temperature: 150°F (66°C)
• Sizing tolerance: Built to 1/8 inch increments

Typical applications

Custom residential, rental, commercial, and legacy HVAC applications prioritizing equipment protection and maximum airflow over fine filtration.

Also worth considering

Shopping on price? Our house brand PrimeShield MAX Airflow (MERV 1–4) 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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