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Our pick if it has to go on the wall

Rabbit Air MinusA2

US MinusA2

$599.95US price, checked Oct 13, 2026

Slim wall-mount purifier for rooms near 280 ft², with $95 yearly filters

Check price at Rabbit Air Full review →

Portable air purifier

Alen BreatheSmart 45i

US BreatheSmart 45i

$449US price, checked Oct 13, 2026

Slim, quiet HEPA purifier with a guarantee tied to Alen filters

Check price at Alen Full review →

Criterion	Rabbit Air MinusA2	Alen BreatheSmart 45i
US price	$599.95Checked Oct 13, 2026 · Price details in the review	$449Checked Oct 13, 2026 · Price details in the review
Three-year ownership estimate	$884.95 Incomplete known subtotal. Not included: energy use.	$725 Incomplete known subtotal. Not included: energy use.
Choose if	You want a purifier on the wall, not the floor, in a bedroom or office up to about 280 ft².	You want a quiet, slim HEPA purifier for one large room and don't mind buying Alen filters every year.
Main trade-off	$599.95 buys a smoke CADR of 180, and Rabbit Air doesn't say who tested that figure.	Filters add $69 to $198 a year, and Alen gives its own airflow figure instead of AHAM smoke, dust and pollen ratings.
Key specifications	CADR (smoke, dust, pollen): 180, 193 and 200; Rabbit Air doesn't name the test standard Room size: Rabbit Air says 408 ft² at 4 air changes an hour or 815 ft² at 2 (8 ft ceiling, top speed). Those match its 218 CFM airflow. On the 180 smoke CADR, 4.8 air changes an hour fits about 280 ft². Noise: 25.6 to 51.3 dBA across five speeds; no per-speed breakdown Power draw: 6 to 61 W (120 V, 0.85 A max); no per-speed or standby figures Filters: Washable pre-filter, medium, BioGS HEPA, one customized filter and activated carbon, plus an ion generator you can switch off Filter life and price: $95 kit (medium, HEPA, customized and carbon) every 12 months at 24/7, or up to 2 years at 12 hours a day; $14.95 spare pre-filter Size and weight: 20 × 21.4 × 7 in; 19.4 lb; wall-mount kit included Controls: Auto mode with particle and odor sensors, pollen mode and a light sensor; remote on the SPA-780A, Wi-Fi app control and no remote on the $619.95 SPA-780N	Clean air delivery rate: 255 CFM on high by Alen's own CADRi figure; 80, 120 and 190 CFM on the lower speeds. No separate smoke, dust or pollen CADR on Alen's page. Room size: 950 sq ft at 2 air changes an hour or 1,900 sq ft at 1, by Alen's figures. Its FAQ says up to 1,600 sq ft. Noise: 24 dB on the lowest speed to 50 dB on high Power draw: 1.6 to 64 W in the spec table; the FAQ says 50 W on high. Alen doesn't say which setting draws 1.6 W. Filter life: Essential (Pure) 9 to 12 months; Advanced (Fresh) and Ultimate (Odor) 6 to 8 months, running 24/7 Filter price: $69, $89 or $99 each; 10% off on subscription ($62.10, $80.10 or $89.10) Ozone: Optional ionizer: under 0.001 ppm when on, 0 ppm when off. Alen lists CARB certification.
Exact variant	US MinusA2	US BreatheSmart 45i
Dimensions	20 × 21.4 × 7 in (height × width × depth). Another spec section on the same page gives the height as 20.25 in. It weighs 19.4 lb, and the power cord is 9.33 ft.	25 in high, 15 in wide and 8.5 in deep, and 14 lb, according to the product page. Alen's support table lists the 45i/FLEX at 19 × 11 × 28 in and 23 lb. That's the same size it gives for the shipping box.
Installation	None needed to stand it on the floor. It plugs into a 120 V outlet. A wall-mount kit comes in the box, and the manual says to drive the hanger screws into studs. On a wall it needs 2 ft of space below the ceiling and 8 in on each side. On the floor it needs 2 ft clear at the air outlet and 8 in at the intakes on each side.	Freestanding, with no installation. It runs from a 24 V external power adapter. The manual asks for a level surface at least 6 in from heat sources such as heaters, with the vents left clear. The Alen Air app adds remote control, scheduling and filter alerts over Wi-Fi.
Materials	Six stages: a washable pre-filter, a medium filter, a BioGS HEPA filter, one customized filter, an activated carbon filter and a negative ion generator. You pick the customized filter: Germ Defense, Toxin Absorber, Pet Allergy or Odor Remover. Rabbit Air says the HEPA media is treated to keep bacteria and mold from growing on the filter itself. The ion generator can be switched off.	One filter cartridge with a prefilter you can vacuum. Essential (Pure) is a True HEPA (H13) filter aimed at dust, pollen, dander, mold and allergens. Advanced (Fresh) adds activated carbon for VOCs, smoke and cooking odors. Ultimate (Odor) adds an odor neutralizer for pet and diaper smells. An optional ionizer can be turned on or off. The front panel comes in White, Oak, Weathered Gray, Brushed Stainless, Graphite or Espresso.
Warranty	Rabbit Air covers defects in materials and workmanship for 5 years from the original retail purchase. Its registration page says registering gets you the 5-year warranty and free round-trip shipping to its service center in the contiguous US. The manual asks you to register within 90 days of purchase. Filters, filter frames and cases, wall-mount brackets and cosmetic damage aren't covered. Rabbit Air may ask for proof of purchase.	Alen gives a 1-year manufacturer's warranty. Its Forever Guarantee extends that if you register the serial number and use only Alen filters. You also need an active filter subscription or proof of an Alen filter purchase in the last 12 months. If troubleshooting can't fix a fault, you get a new unit in year two. From year three you get a refurbished or reconditioned unit, and the guarantee page sets no end date. Alen's support page says to register within 12 months of purchase. The guarantee doesn't transfer and excludes accidental damage, floods and fires. The product page says it needs an active subscription, but the guarantee page also accepts a recent filter purchase.
Returns	90 days from purchase, with a prepaid return label, for orders bought on RabbitAir.com and shipped in the contiguous 48 states. It has to come back like new, in the original packaging with the remote and manual. Items that aren't like new may carry a restocking fee. Replacement filters can't be returned once unwrapped.	60-day trial on orders from alen.com. Alen refunds the purchase but deducts return shipping, using a FedEx label it emails you. Opened filters can't be returned. The refund can take up to 7 business days after the warehouse receives the return. Orders from other retailers go back through that retailer. Alen doesn't say whether the 60 days start at purchase or delivery.
Unresolved questions	Whether AHAM has verified its CADR figures Whether CARB certified it; the readable part of CARB's list held only recent entries Which test standard and lab produced the CADR figures Power draw and noise at each of the five speeds, and standby power Average power on auto, so the yearly electricity cost What warranty cover applies if you don't register	Smoke, dust and pollen CADR from AHAM or Energy Star testing Whether CARB's own list includes the 45i (Alen's linked order file has no readable text) Average power on auto, so the yearly electricity cost Whether the store ships the original 45i or the touch-control 45i V2 named in Alen's CARB and Energy Star files The true size and weight, since Alen's product page and support table disagree How long a filter lasts if you don't run it around the clock How often subscription filters ship

These comparisons use published specifications, not head-to-head tests. Prices and terms are dated. Unknown costs are not zero. Check the exact variant before you buy.