Glass bottles. Easy to clean and no dirt remains in the bottle. Heat expansion is 3 times lower than that of ordinary glass, so the chance of breakage due to cold shrinkage and heat expansion is greatly reduced Lighter and stronger than ordinary glass, less likely to retain odor and dirt, safe and durable With Super Cross Cut silicone teat The Super Cross Cut teat is designed to naturally adjust the flow rate according to the baby's suction power, so no milk will come out when not sucking and avoid choking the baby Suitable for all ages, no need to differentiate between large, medium and small sizes Can be sterilized by various methods, including boiling water, steam, sterilizing solution and microwave oven