Filter King 11.5x21.5x1 Air Filter 4-Pack - MERV 8 Pleated Filters

Our review of the Filter King 11.5x21.5x1 air filter 4-pack finds it best suited for homeowners and renters wanting reliable, no-fuss air filtration on a budget. The single biggest reason to buy is the combination of a true MERV 8 rating and a pleated design that captures more particles without noticeably restricting airflow, so indoor dust and airborne debris drop quickly. The pack is fully manufactured in the United States and arrives as a convenient 4-pack that is easy to install and replace, making routine maintenance straightforward.

Key Features

• MERV 8 rating: Provides effective mid-level filtration that captures common airborne particles while maintaining steady HVAC airflow.
• Pleated design: Increases filter surface area so the filter traps more dust and particulates and lasts longer between changes.
• Made in USA: Fully manufactured domestically, offering consistent construction and materials with an EPA establishment number listed.
• 4-pack convenience: Supplies enough filters for multiple change cycles so homeowners can maintain filtration without frequent ordering.
• Long service window: Rated to perform for up to 90 days depending on household conditions, with recommended changes every 30 to 90 days.

Who It's For

The Filter King 11.5x21.5x1 4-pack is ideal for typical households, apartments, and small offices that need reliable filtration to reduce dust and common airborne particles without the higher restriction of fine filters. It fits standard 1 in filter slots and works well for users who want an easy, regular replacement schedule and value domestic manufacturing.

People who require medical-grade filtration, extremely allergen-prone environments, or extremely long filter life should look at higher MERV ratings or thicker filters; likewise, anyone needing custom cut sizes or nonstandard thickness should consider alternatives.

Pros & Cons

Pros

• Good balance of filtration and airflow due to the MERV 8 pleated media.
• Made in the USA with consistent materials and construction.
• 4-pack provides value and simplifies scheduled replacements.
• Easy installation: open, slide and close works in most standard housings.

Cons

• Actual thickness is 0.75 in, not a full 1 in, so check fitment if housings are tight.
• Some users reported occasional difficulty during installation in older or irregular housings.

Specifications

Brand	Filter King
Pack size	4-pack
Rated size	11.5 in x 21.5 in x 1 in
Actual size	11.5 in x 21.5 in x 0.75 in
MERV rating	MERV 8
Made in	United States (EPA Establishment 103501-FL-1)
Recommended change interval	30 - 90 days

Our Verdict

The Filter King 11.5x21.5x1 air filter 4-pack is a practical, value-oriented choice for most homes and small offices because it balances effective particle capture with low airflow restriction and easy installation. For those who want reliable, domestically made 1 in replacement filters and plan routine maintenance, this set is a good buy; users needing thicker media or medical-grade filtration should consider other options.

Frequently Asked Questions

How often should these filters be changed?
Filter King recommends changing 1 in filters every 30 to 90 days depending on household conditions and usage.

Will the filters fit a standard 1 in slot?
The filters are sold as 11.5 in x 21.5 in x 1 in rated but the actual thickness is 0.75 in, so they fit most standard housings but check tight slots before purchase.

Are these filters truly made in the USA?
Yes, the product is fully manufactured in the United States and lists an EPA establishment number for reference.