My baby was in the NICU and learned how to suck using the enfamil nipple. Even at 4 months old he can't use the fancy kind they have today. He just doesn't understand how to shape his mouth. These bottles and Dr. Browns are the only ones skinny enough to fit the enfamil nipple. Best part is, they cost less than $3 dollars a bottle compared to the popular brands that run $16 to more than $20.00 a bottle. They may not be the cool thing, but they work.