Filter King 39.5x36.5x1 Air Filter 4-Pack - MERV 8 Pleated Filters

In this review the Filter King 39.5x36.5x1 Air Filter 4-Pack is evaluated for homeowners and maintenance pros who need a reliable, easy-to-install 1 in replacement. The bottom line: this set delivers consistent filtration with a MERV 8 rating and a pleated design that captures more airborne particles without noticeably restricting airflow. For anyone replacing furnace or A/C filters in large grills or return housings, the real-world advantage is a better fit and visible dust reduction inside two days.

Key Features

• MERV 8 rating: Provides moderate filtration that captures common airborne particles while maintaining good airflow for HVAC systems.
• Made in USA: Fully manufactured in the United States using consistent materials and construction practices.
• Pleated design: Extends filter life and traps more particles compared with flat media, reducing dust buildup on HVAC components.
• Actual size accuracy: Labeled as 39.5 in x 36.5 in x 1 in with an actual thickness of 0.75 in, which helps ensure a correct fit for undersized housings.
• Up to 90 day use: Rated to last up to 90 days depending on conditions, giving flexible replacement intervals of 30 to 90 days.
• Easy installation: Simple open, slide and close design makes swapping filters quick during routine maintenance.

Who It's For

This 4-pack is best for homeowners, property managers, and HVAC technicians who need a reliable, mid-level filtration option for furnaces and residential air conditioners. It suits systems where MERV 8 balance of particle capture and airflow is preferred, and for households that want filters fully manufactured in the United States.

Those needing hospital-grade filtration, allergy-specific media, or thicker multi-inch cartridges should look elsewhere; this product is a 1 in pleated filter optimized for standard residential returns rather than specialized environments.

Pros & Cons

Pros

• Consistent MERV 8 performance that traps common household particles without major airflow restriction.
• Made in USA construction with predictable quality and materials.
• Good fit and finish noted by customers, which reduces the chance of gaps or poor sealing.
• Four filters per pack provide ready replacements for several months of routine use.

Cons

• Actual thickness is 0.75 in so tight 1 in slots may need careful fitting to avoid wobble.
• Not designed for high-efficiency medical or HEPA-level filtration needs.

Specifications

Brand	Filter King
Pack Size	4-pack
Rated Size	39.5 in x 36.5 in x 1 in
Actual Size	39.5 in x 36.5 in x 0.75 in
MERV Rating	MERV 8
Made In	USA (EPA Est. 103501-FL-1)
Recommended Change Interval	30 - 90 days

Our Verdict

The Filter King 39.5x36.5x1 4-pack is a practical, cost-effective choice for residential HVAC maintenance when you need reliable MERV 8 filtration and consistent fit. It offers American-made construction, easy installation and a pleated design that noticeably reduces dust in ordinary homes, making it a strong value for routine replacement cycles.

Frequently Asked Questions

How long do these filters last?
They are rated to last up to 90 days, with recommended replacement intervals of 30 to 90 days depending on usage and environment.

Are these filters made in the United States?
Yes, they are fully manufactured in the USA with EPA establishment number 103501-FL-1 noted by the manufacturer.

Will the thickness cause fit issues?
The actual thickness is 0.75 in so some tight 1 in housings may need careful insertion, but customers report a good overall fit in standard return slots.