Philips Avent Natural Glass Baby Bottle - 4oz Imported Pure glass, made of premium quality borosilicate glass. Heat and thermal shock resistant The most natural way to bottle feed. Natural nipple shape and ultra soft feel makes it easy for baby to combine with breastfeeding Wide breast-shaped nipple promotes a natural latch on Airflex valve integrated into the nipple is designed to reduce feeding issues by venting air away from your baby's tummy A range of flow rates are available for your growing baby. This bottle includes a Newborn flow nipple