From the seller

Type and Features: These are wide-neck silicone teats designed for Dr. Brown's Options+ wide-neck bottles. They feature a breast-like shape for natural latching and are part of Dr. Brown's Natural Flow system, which includes an anti-colic internal vent system to reduce colic, spit-up, burping, and gas, and to preserve nutrients in the milk. Level and Age Range: This is a Level 3 teat, which offers a medium-fast flow and is suggested for babies aged 6 months and older, though the ideal flow rate may vary based on the baby's feeding style. Material and Safety: The teats are made of 100% soft silicone and are BPA-free. They are safe for use in the top rack of a dishwasher and in electric and microwave sterilizers, or can be sterilized in boiling water.