They work exactly as advertised and seem to be made of high quality material that will last a long time and not collect mold or deform. However, they are a very loose slip fit with my collection cups so when I pour my collected milk out of my collection cups I have to make sure I have tight pressure with my thumb over the diaphragm or else the diaphragm falls out and the little bit of milk that gets trapped in diaphragm’s well spills all over the place. I have zero issues if I remember to hold the diaphragm tightly when pouring, but I wish the diaphragm fit tighter with the collection cups so I don’t have to be super concerned with the possibility of the diaphragms falling out every time I pour. But again, they work as advertised and have a tight fit with the pump so they perform when pumping exactly as advertised