This 4-pack of Dr. Brown's 2oz anti-colic baby bottles with preemie nipples and 3-pack of 60cc anti-colic bottles offer a complete feeding system for premature or newborn babies. The 2oz bottles feature an ultra-slow preemie nipple flow specially designed for premature babies or those with feeding difficulties. These bottles integrate Dr. Brown's clinically proven internal vent system to reduce colic by decreasing spit-up, burping and gas. The vent system also preserves nutrients and aids digestion. The breast-like nipple shape provides a natural latch and comfortable transition between breast and bottle. The 60cc bottles are compatible with all 8 of Dr. Brown's nipple flow rates and most electric breast pump systems. Both bottle types are made from BPA-free plastic and are dishwasher, microwave steam bag, electric steam sterilizer, and autoclave safe. Combining both bottle types creates a versatile system to meet all of a premature or newborn baby's feeding needs.