Instruction: Output yes if the supporting document can answer the given question. Otherwise, output no.

Input:
Question: Would this work on a ceiling vent?
Document: These are very thin. It works on my floor vent but I highly doubt it would work on a ceiling vent. Does not have a strong hold at all. Disappointed.
I have ceiling vents and these covers were advertised as able to work in this application they fell off immediately. I would not recommend this item to anyone.
I ordered these vent covers, but they did not magnetically stick to my vents!! I was very disappointed that they would not work for me, even though they should have.
You may as well stick duck tape over the vent these do not work! I read the other bad reviews and figured i would give it a try. I figured there is at least one good review on the vent cover . So i would give it a try...lol They fell right off! THEY DONT EVEN STICK TO ANOTHER MAGNET THAT I HAVE..LOL
I read many reviews of people that used them for ceiling vents or to block supply ducts, so I bought them thinking they would function better on a return vent. The covers I received had a slight curl to them, the magnetic force was not enough to hold them against my return vent and they just fell off. I ended up just detaching the return grate from the wall and cutting a piece of cardboard that fits inside the grate on the inside, then screwing it back to the wall.
Don't waste your time/money if you want to block a ceiling vent. Simply won't adhere. Apparently you can pull the vent out and insert it on the inside. But a piece of cardboard or anything else will work if this is the approach you take.
I bought these to cover a ceiling mounted vent in an unused room. The magnet is not strong enough to hold the cover 'up'. It seems like it will work fine on floor vents, but this did not work for me on my ceiling vent.
These magnets are not very magnetic. Something with a reusable adhesive would be a more appropriate solution. Get to work folks,
They are large (about 5" x 10") white colored magnets. I would rate them higher, but the magnetic backing is not very strong. I have to position the magnets so all airflow is not restricted - just redirected - otherwise I am certain the obstruction created by the magnet would cause them (the magnet) to dislodge. These may not be the perfect application for everyone's use, but may just work for you - or your wine cellar of an office.
This product does exactly what it should for vents mounted on the floor, but will not stay attached to wall or ceiling mounted vents. You would have to glue, tape, or use additional magnets to hold this in place in those locations.
Answer: yes