Let me start by saying these air vent deflectors solved my biggest office annoyance: freezing AC blasting directly on my head all day. The adjustable design (9-15 inches) fits most standard vents, and those magnets? *Chef's kiss* when installed correctly. Pro tip: press until you hear a 'click' for maximum hold.
The transparency is nice - doesn't look obtrusive on ceiling or wall vents. I've redirected airflow perfectly under my sofa where toys kept blocking vents. Energy savings? Absolutely notice less HVAC runtime since air goes where we actually need it.
BUT... durability is questionable. The hard plastic feels sturdy until impact - dropped one from waist height and it shattered like Christmas ornaments. Also wouldn't recommend for high-traffic floor vents (RIP to that reviewer's mom-stepped deflector).
Installation varies wildly by vent type. My ceiling ones held perfectly, but a colleague struggled with their metal thickness. The 4-pack is great value though - I use extras seasonally when rearranging rooms.
Final verdict? Fantastic for temporary/light-use redirection at this price point, but handle like fine china and maybe avoid putting them in harm's way.