Glasfloss 18x24x4 MERV 10 Pleated Air Filters - 2 Pack

In this review the Glasfloss 18x24x4 MERV 10 pleated filter pack is assessed for homeowners and light-commercial users who need a balance of improved particle capture without excessive airflow restriction. The bottom line: this two-pack of filters delivers reliable MERV 10 filtration in an actual size of 17-1/2 x 23-1/2 x 3-3/4, making it a straightforward replacement when the system calls for nominal 18x24x4 filters. For those prioritizing cleaner indoor air and a US-made option, the Glasfloss filters are an easy choice as long as the system accepts the slightly undersized actual dimensions.

Key Features

• Actual and nominal sizing: The filters use an actual size of 17-1/2 x 23-1/2 x 3-3/4 which fits systems labeled 18x24x4 while ensuring a snug fit in most standard housings.
• MERV 10 filtration: The MERV 10 rating captures a wide range of airborne particles, offering noticeably better particle reduction than basic fiberglass filters for improved indoor air quality.
• Comparable ratings: The filters correspond to an MPR of roughly 600 to 800 and an FPR of 5 to 6, giving a clear sense of their mid-range performance compared with other rating systems.
• Low pressure drop: Pressure drop is reported comparable to a MERV 8, which helps maintain system airflow and efficiency while delivering higher filtration performance.
• Made in the USA: Domestic manufacture can be important to buyers seeking locally produced HVAC components and consistent quality control.
• Two filters per pack: The quantity of two makes it convenient to change filters on a bi-monthly schedule for many households, simplifying maintenance.

Who It's For

The Glasfloss MERV 10 pleated filters are best for homeowners, renters, and small commercial spaces that need a step up from basic throwaway filters but still want low resistance to airflow. They suit systems that accept nominal 18x24x4 filters where the actual dimensions listed will fit the cabinet or slot without forcing modifications.

Customers who require a thicker 5 in or 4-3/8 in depth filter should look elsewhere, because these Glasfloss filters do not replace deeper media. Also, those who need true high-efficiency hospital-grade filtration should consider higher MERV-rated or specialized HEPA-compatible solutions.

Pros & Cons

Pros

• Reliable mid-range MERV 10 performance that improves particle capture over standard fiberglass filters.
• Low pressure drop similar to MERV 8, helping preserve fan efficiency and HVAC performance.
• Made in the USA with consistent sizing and construction for home and light-commercial use.
• Two filters per pack simplifies routine replacement schedules for many households.

Cons

• Actual thickness is 3-3/4 in, so it will not replace systems that require true 5 in or 4-3/8 in depth filters.
• Not intended for environments that require very high MERV levels or HEPA-grade filtration.

Specifications

Our Verdict

The Glasfloss 18x24x4 MERV 10 pleated filters are a practical upgrade for most homes and small commercial systems that accept nominal 18x24x4 sizing. They strike a good balance between improved particle removal and low pressure drop, and the two-filter pack offers convenient value for routine maintenance. Purchase them when the system accepts the actual 17-1/2 x 23-1/2 x 3-3/4 dimensions and you want dependable, US-made filters without moving into high-resistance, high-MERV options.

Frequently Asked Questions

Will these filters fit my 18x24x4 slot?
They are nominally 18x24x4 but have an actual size of 17-1/2 x 23-1/2 x 3-3/4 in, so they fit most housings labeled 18x24x4; verify your slot clearance before buying.

Can these replace a 5 in depth filter?
No, these are not a replacement for 5 in or 4-3/8 in depth filters and should not be used where a deeper media is required.

How often should they be replaced?
Replacement frequency depends on use and environment, but two filters per pack suits many households on a bi-monthly or quarterly rotation depending on dust and occupancy.