SAFE MATERIAL : PPSU material will not absorb odor or color. Repeated sterilization is also safe without any deformation. BPA and Phthalate free. Microwave safe. EASY TO USE AND CLEAN : Simple Parts are easy to wash and assemble. Dishwasher safe. REDUCE NIPPLE CONFUSION : Designed to reduce bottle rejection and nipple confusion. ANTI-COLIC VALVE : Anti-colic valve is designed to reduce colic and discomfort by sending air away. ECONOMICAL : Grosmimi bottle is compatible with the Grosmimi straw cup. Just replace nipple to straw. Grosmimi Baby Bottles are made of PPSU. Material commonly used for medical devices requiring repeated steam sterilization. It is incredibly durable and temperature resistant. The nipples are made of soft silicone material that reduces papillary confusion, and two air valves regulate the air circulation inside and outside the bottle for comfortable feeding. 10 oz bottle comes with Stage 2 nipple.