Safe Material: Beilastarx glass baby bottles are made of high-quality borosilicate glass, which is pure, clear and free of impurities, and does not contain BPA or BPS. It is heat-resistant and easy to clean and sterilize. Different Age Stages: 120ml/4oz with Slow Flow SS nipple for 0+ months, 180ml/6oz with S nipple for 1+ months, 240ml/8oz with M nipple for 3+ months. Meet the needs of all stages of the baby. Silicone Nipple: The nipple is made of food-grade silicone, which is super soft and allows the baby to suck naturally. There are air holes at the bottom of the nipple to balance the internal and external pressures, separate the milk from the air, and prevent the baby from inhaling too much air and causing colic and flatulence. Breastfeeding-friendly: Glass bottles with natural response nipples are close to breastfeeding, allowing babies to feed at their own pace, just like the natural feeling of breastfeeding, and making an easy transition between breastfeeding and bottle feeding. Easy to Assemble and Wash: The wide mouth and streamlined body of the bottle make it easy to clean and hold. It can be cleaned in many ways, dishwasher safe (top rack only), bottle warmer, microwave sterilizer and boiling water safe. Glass Baby Bottle with Natural Response Nipple