Very good material, the only downside and for this reason 4 stars are the plastic buttons which are also close.

5 stars for the price/features ratio.
For installation, the bases are the ones with the inflatable plug, commonly the installation (or removal) is done exclusively from the top without the need to bend down and search behind the toilet bowl. You just need to "align" the lid with the bases on the toilet bowl and screw it in with a screwdriver, and it stays in place. Note that the screws don't need to be tightened too much because the plastic plug inside the toilet bowl holes can break, and then it won't be able to stand (you will either need to find another plastic plug or use different screws that will fit in the traditional way with threads from the bottom).
Also, something that is not mentioned in the description is the mechanism for directly removing the lid from the bases, which remain on the toilet bowl (to clean it separately, etc.). You press the button that appears below in the center in the second photo and it releases, and then you simply attach it back to the bases.
The screws and the metal lids of the bases are stainless steel, but I won't vouch for it (in any case, they are not magnetic). What I didn't like so much is that the metal covers of the bases are not attached, they are simply placed on top. That means if you move them, for example, with your finger, they play around, maybe it's more convenient that way to remove them every time you clean (as long as you don't lose them).
As for the disadvantages, I will mention the fact that the protective film of the metal lids (in my case at least) had become one with them (as if it was paint), especially at the edges, and it took me a long time to completely remove the residue without scratching the surface of the lids.
Second disadvantage, it has some minor flaws (Chinese-made), for example, the elastic pads of the lid that come into contact with the rim of the toilet bowl when you lower it do not fit perfectly inside their seats, and the plastic of the upper surface right above these seats has small dents. If it didn't have these small details, it would be the perfect lid in terms of price.

EDIT 19-12-2022: Almost a year later, no problems with the lid, but it is worth noting that I gave it a 5-star rating based on the price at the time, which was a total of €19.50 (including shipping costs).

It would be advisable to have an installation manual. Once you find the sequence of steps, you can literally install it in 2 minutes.