Which in accordance with breast cover of human physiology. work in with soft bubble shaped silicone bumo. massage breast comfortable. gentle and comfortable suction. let mother experience the same nature as baby sucking. Size bottle mouth design used in standard diameter bottle and wide diameter mouth bottle. Considerate dustproof design to ensure product clean, sanitary, healthy. Material conforms tc national health inspection standard. no BPA. the product has high transparency strong hardness, easy to clean, and not easily derorned, please use securely.