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Trane BAYFTFREXM2 (2-Pack) - 25 x 5 inch Perfect Fit 5" Expandable Replacement Air Filter

Size Guide

Trane BAYFTFREXM2 (2-Pack) - Perfect Fit 5" Expandable Replacement Air Filter

  • Nominal Size: 25" x 5" - Requires: Retrofit Frame Kit Features
  • Trane recommends this filter be replaced every 6-12 months for maximum efficiency
  • 2 Filters

Trane BAYFTFREXM (2-Pack) - Perfect Fit 5" Expandable Replacement Air Filter This is an authentic and brand new Trane BAYFTFREXM (2-Pack) - Perfect Fit 5" Expandable Replacement Air Filter Trane recommends this filter be replaced every 6-12 months for maximum efficiency and effectiveness. Replacement Frequency depends on the condition of the environment and use of area being filtered. Specifications: - MERV Rating: 8 - Filter Life: Up to 12 Months - Nominal Size: 25" x 5" - Requires: Retrofit Frame Kit Features: - Easy Sliding Cartridge for Quick Replacement - Evenly Spaced Pleats Capture Maximum Particles - Helps Keep Your HVAC System Operating at Peak Performance

Customer Reviews

Based on 6 reviews

Great price Fast delivery


Simple once you figure out how to assemble . very sharp edges on metal screen will cut you easily .will order again!

Happy with the company and the filter

Atomic Filters was a great company to do business with. I received exactly what I needed quickly and they were kind enough to send emails along the way. In fact I believe I'm now on a "courtesy change filter notice" which I really need. I plan on continuing with this company in the future.

Elbow Grease

These filters were the exact model I needed. Arrived within a week. These fit into a plastic frame that secures with a snap closure, however the holes through the various layers of cardboard were misaligned. Had to use create my own using a screwdriver. Maybe they are so inexpensive because they didn’t pass quality control?


Good service

Nominal Vs. Actual Sizes: Finding the Right Air Filter Size

Buying the Correct Size Air Filter- The Most Important Thing to Know 

When you are buying your air filter online most important thing to know is Air Filters have two sizes that you need to understand the Nominal size and the Actual Size. Not understanding these numbers often leads to consumers purchasing a filter that does not fit their Furnace or HVAC system. See the complete list of Air Filters by Size Rating and Brand.

Nominal vs Actual air filter size by Atomic


Understanding Nominal Filters Size Could Save You Time and Money

Not understanding the Nominal Filter Size is the primary culprit for incorrectly purchased filters.The Nominal Size is the usually the dimensions used to Label the filter. For instance 16x20x1. These dimensions are a rounded value on the filters actual measurements. The actual measurements on this filter may be 15.5x19.5x.75, but that could vary by brand and manufacturer. So in order to make sure you have the correct size filter, especially if you are replacing with a different brand it is important to confirm the actual size on the filter. When purchasing filters on the internet the Nominal size is usually found in the product title.

Actual Filter Size- The Key to Making the Right Replacement Filter Purchase

The actual size as you might have guessed are the actual dimensions of the filter by length, width and thickness. This size is often on the filter right below the Nominal size and is usually labeled as the actual size. When you are buying a filter online the actual size is sometime in the product bullet point or the product description. If your filter does not have actual dimensions on the outside of the filter, you can measure you filter to get the correct dimensions. Some brands have a foam gasket on the outside of the filter, in this case, you will want to make sure you have a compatible actual size and that it also has the foam to ensure a snug fit. 

Lennox Air Filter X0851 with Foam strips

Examples of Nominal and Actual Sizes

 Size  Example 1  Example 2
Nominal Size 20x20x1 16x20x1
Actual Size 19.5x19.5x.75 15.75x19.75x.75


 Furnace filters should fit securely but should not have to be forced into position. If you have to force the filter into its slot, then it is probably too big. Forcing an improper filter size in a filter can cause it to buckle, damaging the filter or reducing its ability to function properly. Filters are a smaller than their slot to allow for easy replacement. Some HVAC units may need a filter with dimensions that are unique or uncommon. In these cases, a custom filter needs to be ordered.

Find Your Filter Sizes Easy in 1" Deep Filters , 2" Deep Filters, 4" Deep Filters