Quality Materials: yanyoyo natural glass baby bottle is made of high-quality borosilicate glass, is BPA-free, lead free, the cap is well sealed and will not leak, the scale is clear, and gives the mother better control over the amount of milk, it is heat and cold resistant, so it can be safely stored in the refrigerator or heated. Soft Natural Nipples: Ultra-soft, food-grade liquid silicone nipples mimic the natural feel of breastfeeding and help breastfed babies suck naturally, the bottom of the nipples has intelligent pressure regulating valve, balance internal and external pressure, milk and air separation, to avoid the baby breathing too much air caused by colic flatulence, and newly designed larger nipples better protect baby's lips. Easy to Clean: Glass bottles for babies are of wide mouth design makes the bottle easier to clean, does not hide milk dirt, the inner wall is smooth, and there will be no scratches when cleanse. Baby bottles can be cleaned in hot water or steam. Package: Our baby bottle gift set contains 4 pcs newborn baby bottles(3oz), 4 pcs slow flow nipples(SS), to meet the mother daily feeding needs. After Sale: We always provide customers with quality products and good service. If you have any questions during the shopping process, please feel free to contact us, all questions will be answered and resolved within 12 hours ! yanyoyo natural glass baby bottles with natural response nipples allow babies to control the speed of milk, just like breastfeeding. The unique design of the nipple only releases milk when the baby actively drinks. When stopped to swallow and breathe, no milk is released. Mimicking the shape and soft feel of the breast, coupled with the fact that the baby can control the flow of milk like breastfeeding, makes it easier for the baby to accept. The anti-colic valve on the nipple reduces colic and discomfort by draining the air from your baby's tummy. The ergonomic shape makes it comfortable for parents to hold. Simple assembly and easy cleaning. This glass baby bottle is made of high-quality borosilicate glass, a BPA-free material. It is heat and cold resistant, so it can be safely stored in the refrigerator, heated, and easily cleaned and sterilized.