Flintar B4-Fresh Replacement Filter, Compatible with Alen BreatheSmart Flex and 45i Air Purifier, H13 Grade High Efficiency Air Filtration with 12 oz. Activated Carbon Pellets, 1-Pack

Works like OEM. It’s a good replacement and quickly clears the indoor air of smells pet smells smoke, etc..

Fit the brand name at half the cost!!

Excellent. Would but again.

Bought this because Alan filters are way too overpriced. This one is a pretty good replacement, contains a good amount of carbon from what I can tell, and includes replacement pre-filters for large dust and hair, which I vacuum weekly and replace every 4 months. However this filter is just a bit small length-wise, so there is about a half an inch gap on the top where air can get through, so have to make sure it’s pressed tight against the inlet. If you have some extra foam you can cut it and put it in between to close the gap.

Excellent but expensive

Works great with Alen 45i air purifier and the extra covers are nice if you have pets because all the pet hair gets caught by this first layer which you can just peel off, trash, and replace rather than having to periodically clean it. I can't tell that it works any better or worse than the OEM filter.

I truly am satisfied with the Flintar B4-Fresh Replacement.

Excellent filter for my air purifier. Fits snuggly. Comes with 3 prescreens to extend the life of primary filter