(Last Updated On: March 28, 2023)

Alen BreatheSmart FLEX Air Purifier

air filter for pet allergies from dogs

By Becky Dotson

12 min read

The Alen BreatheSmart FLEX air purifier has a sleek design that will blend nicely in any room of your home. This unit works best in medium to large-sized rooms and uses a true HEPA filter to pull dust, mold, allergens, pollen, pet dander, and fur out of the air. Depending on the filter you choose, the FLEX also rids your home of odors, bacteria and viruses, cigarette and wildfire smoke, as well as fumes from aerosol sprays and other chemicals.

Alen Breathesmart FLEX

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Features and Specs

The FLEX is a relatively small machine that is effective in larger spaces. There are six different panel colors to choose from, so they will blend in or match the décor in any room of your home. The FLEX cleans the air every 30 minutes in rooms up to 700 square feet. Its no-frills design makes it perfect for someone who wants optimal air purification without many features and extras.

  • Dimensions: 25 x 15 x 8.5
  • Low noise level
  • Weighs 15 lbs.
  • Covers up to 700 Sq Ft


Energy Star certified

Four fan speeds

Lifetime warranty

Multiple panel color choices


No WiFi or remote-control capabilities

Filter replacement cost

Lifetime warranty only available with filter subscription

About Alen

Alen is an air purifier company based in Austin, Texas that’s been in business since 2005. As one of the top brands in the air purifier industry, Alen considers itself to be an innovator in the industry. With a mission of improving its customers’ quality of life, the company also prides itself on providing superior customer service for its customers.

With a commitment to quality, technology, and sustainability, Alen offers a lifetime guarantee on all products.

Alen BreatheSmart FLEX Air Purifier Review

The BreatheSmart FLEX is the company’s most popular air purifier for commercial use. But it also works well in homes where the room it’s placed in is 700 square feet or less. The unit will purify the air every 30 minutes.

It has four fan speeds. The lowest setting is whisper-quiet, while the highest speed emits ‘pink noise’ –  comparable to the sound of a gentle rainfall. The plug-in cord is more than seven feet long, making it easy to move around the room to areas where you may need it more.

There are four filter types to choose from – each with different benefits and prices. Each filter is designed to last up to a year before it needs to be changed.

  • Alen BreatheSmart FLEX True HEPA-Pure Filter: B4-Pure/FL40-Pure

The standard filter that comes with your FLEX system is a medical-grade, true HEPA filter that removes 99.99 percent of dust, pollen, pet dander, and many other allergy triggers. The replacement filter will cost about 70 dollars.

  • Alen BreatheSmart FLEX True HEPA Fresh Filter:  B-4-Fresh/FL40-Silver-Carbon

True HEPA Fresh Filter costs around 90 dollars without the filter subscription. It has all the benefits of the standard, medical-grade HEPA filter that captures 99.99 percent of the contaminants in your air. But it also has activated carbon which helps protect against toxins like pollution, smoke, and other volatile organic compounds.

  • Alen BreatheSmart Flex True HEPA-OdorCell Filter:  B4-Odor/FL40-MP

This filter runs around 100 dollars, and Alen markets it as the best filter for homes with pets and kids. In addition to removing allergens and other pollutants from the air, it uses what the company calls nontoxic technology to get rid of pet and household odors at the molecular level.

  • Alen BreatheSmart FLEX True HEPA-Smoke Filter:  FL40-H

This filter is a heavy-duty smoke filter using more activated carbon than the B-4-Fresh/FL40-Silver-Carbon filter. It targets pollution, toxic chemical fumes, and even wildfire smoke. Like the others, it captures 99.99 percent of all dust and allergens in the air of your home. It will cost you around 120 dollars.

Alen also sells certified refurbished air purifier systems at a discounted price online. Some refurbished units have never been used or operated, and all come with the company’s lifetime guarantee if you buy the filter subscription program.

Our Verdict

The Alen family of products performs well against its competitors. The BreatheSmart FLEX is an excellent option for medium to large rooms, like a living room/kitchen open floor plan. Its truly medical-grade HEPA filtration system rids your home of 99.99 percent of airborne irritants and is an excellent option for asthma and chronic allergy sufferers.


Alen designs high-quality air purifier systems that are built to last. Alen products are covered by a lifetime guarantee as long as you register the purifier with them and subscribe to the filter replacement program. 

The company states its products, including the BreatheSmart FLEX, have been independently tested in labs to show they effectively capture virus particles in the air. SleepScore Labs also conducted a study on the FLEX and found it improved sleep for people who suffer from allergies.


The Alen BreatheSmart FLEX air purifier will cost you between 350 and 400 dollars in addition to the cost of filters designed specifically for the unit. The true HEPA filter will last between nine and 12 months, even if it’s run 24 hours a day, seven days a week. Depending on the filter you choose, it can cost anywhere from 70 to 120 dollars to replace. The filter subscription program will save 10 percent on every purchase. The company also offers a third-party financing option when buying the unit.

The FLEX is Energy Star-certified and pulls a relatively low amount of energy, so even if you use it all the time, you shouldn’t see much to any difference in your electric bill.

Customer Service and Reviews

Overall, customers seem to love this air purifier. It’s small, easy to maneuver and move around, and effective. Many customers say they choose the FLEX (and other Alen products) because of the lifetime guarantee. Alen stands out from its competitors as the only air purifier company offering a lifetime guarantee in an industry where a one or two-year product guarantee is status quo. Should your unit need repair, Alen’s in-house experts will help you fix it or ship you a replacement for free.

Like most companies, you will find complaints about Alen’s products and services on the Better Business Bureau’s website. All of them have been addressed and resolved by the company. 

Alen’s Customer Support page on its website is very thorough. It’s broken down into categories to help you quickly determine where to go for help. There’s a live chat feature for quick feedback, along with a phone number and question submission form. You will also find product owner’s manuals there in case you misplace yours.

Alen BreatheSmart FLEX Customer Reviews:

Highly recommend this product.

“Highly recommend this product. It’s very quiet in operation and very easy to use.”

— Alen BreatheSmart FLEX review via Home Depot 

The experience buying the Flex was painless.

“The experience buying the Flex was painless. Customer Service was helpful and accessible (got a human!)”

Alen BreatheSmart FLEX via Google 




Overall, the Alen BreatheSmart Flex air purifier is an excellent choice for allergy and asthma sufferers. Its small, sleek design makes it easy to place around your home and helps it blend in as part of the furniture. Its 350-to-400-dollar price tag makes it relatively expensive, but its long-lasting filters and lifetime guarantee make it a worthy investment.

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