With a new twist on an iconic classic, Evenflo Feeding's Glass bottles offer style on top of superior sanitizing, recycling, and sustainability. The tempered glass bottle includes a a ProflowTM Integrated Venting Nipple. These silicone nipples rapidly vent, directing air bubbles into the bottle, not baby's tummy which significantly reduces gas, colic, and fussiness. Expertly designed for easy assembly and leak-free feeding, the simple, one-piece nipple and vent means no extra parts to clean or lose.