The tip isn’t sealing good enough so when you’re using it with mouth like a straw, you suck more air than water. The adapter used for attacking the bottle is also not very secure. You can easily bust the seal. The membrane itself seems to look good but when i tried to do integrity test it didn’t pass it, but this tests effectiveness is a bit controversial especially on new filters so that’s just an information to know, not a verdict. There is a newer „filterwell” model that has a plastic thread and seems to be quite well designed unlike this one.