I have made many attempts to use them, I have not managed to match them with any device. Useless for me.

Bad :) it doesn't fit well, it doesn't suction at all. It is only useful if you have containers that are exactly the size of the lids and even then it doesn't close properly. It didn't help us at all. It is not a membrane alternative as we imagined and that's why we bought it.

It is not easy to apply and it is not completely waterproof even when applied correctly. It was not what I expected

I would like the silicone to be of slightly better quality and to stretch a little more and hold without slipping. Other than that, it's fine! It does its job

They do what they say.. they seal very well and water doesn't leak even yet!! Unfortunately, in my order, the largest one had a small hole, so I don't use it much.. but the rest are fine!!