Review on Maymom Dome Caps, Screw Rings, Sealing Discs Compatible With Avent Natural Bottles, Avent PP Bottles Or Natural; No Nipple Included. Convert Avent Classic Bottle Into Natural by Kevin Hauck

These things are very helpful for storing extra milk without using a nipple and cap. They don’t fit terribly well on the avent natural rings. They barely fit (as in are close to being too loose to stay) at room temperature, and then after refrigeration they get loose. The only thing keeping them in place is the pressure from the ring against the bottle top. That said, they work great on the avent classic rings, and we seem to have enough of those around. Would still recommend, just wanted to make sure that caveat was known