After using these Y6604 filters for several months, I can confidently say they deliver decent performance for the price. The air quality in my home noticeably improved – fewer dust bunnies and my allergies aren't acting up as much.

The installation was a breeze. They slid right into my Lennox PureAir system just like the OEM filters, though I did notice they're slightly shorter (about 1/4 inch) than the originals. My HVAC tech confirmed they'll work fine despite this minor size difference.

What surprised me most was how sturdy these filters feel. The carbon layer seems substantial, and the pleats hold their shape well. After three months of use, there's no sagging or deformation like I've seen with cheaper filters.

That said, I completely understand the concerns about missing UL certification. While mine have performed well so far, the misspellings on the packaging do make me question quality control. For peace of mind, I might splurge on OEM filters next time.

The packaging could definitely be better – my first shipment arrived with a dented box (thanks, Amazon delivery), but the seller promptly sent replacements. Pro tip: consider ordering during dry season if possible!