Multiple options available:

https://www.drbrownsbaby.com/product-category/baby-bottle-nipples-bottle-feeding/

Additional Resources: Choosing a Bottle Nipple handout

For healthcare providers: to order from Dr. Brown’s you must set up an account first. Dr. Brown’s Medical Rep: Sandra J. Aubuchon saubuchon@handi-craft.com
www.drbrownsbaby.com/medical

Additional resources: see Table 18: Nipple Flow Rates