We have tried numerous sippy cups with no success. This is such a great idea! Fits very well over numerous different cups and bottles.
We've used another brand of tops and they would tear within a week of use. I had went through at least 6 lids. These are nice and thick; easier to put onto a cup, whether glass, plastic or silicone and will last MUCH longer!! Definitely looking forward to not having to buy another set unless these get lost or damaged from something other than regular use!
I like that you don't have to buy a million different sippy cups that all have different size lids. I use these with our replay cups. They even work with the replay sippy cups (the ones that look like the cups), just in case a lid grows legs and walks off. The silicone spill proof piece will weaken over time. Especially if your little one likes chew or push their finger down the top. This was over the course of a year and some change. They are definitely easier and cheaper to replace than a specific sippy cup. The quality is good and the silicone is a thicker then other brands. The only reason I gave it 4 out of 5 stars is it makes it a million times easier to put on when the cup is sitting on a flat surface. If you have stiff hands than this might be harder to put on. Over all I plan on continuing to purchase these.