The bottle body is made of transparent and heat resistant borosilicate glass. Wide caliber bottle mouth for easy brewing milk and cleaning bottles. Vented soft and flexible nipple design helps reduce colic, gas and spit-up. It is not easy to break under high temperature such as pouring boiling water. How to use: Hand-wash the new bottles with soap and lukewarm water. Sterilize the bottles in hot water for 5 minutes. Open the cap and nipple and fill the bottle. Secure the nipple in place and feed the baby. After use always wash and sterilize the bottles to keep the bacteria away. Proper sterilization of bottles will help prevent infection-related illnesses in children. Caution & Warnings: Store the clean and dry bottles in a cool and moisture-free place Replace the teats periodically Store the bottle away from direct sunlight Never leave a child unattended while feeding. Check for cracks and breakage before using the glass bottles Ingredients: 1pc of glass feeding bottle, BPA Free