Our replacement nipple rings are meticulously designed to ensure flawless compatibility with all Medela bottles, including both 5-ounce and 8-ounce sizes. Engineered for precision, these rings fit perfectly with Medela's range of bottles but please note they are not suitable for Enfamil ready-to-feed bottles or Philips Avent bottles. Each set includes six high-quality, BPA-free collar rings, allowing you to replace old or lost rings or keep extras at home or daycare for convenience. These collar rings are crafted to fit every Medela nipple securely, guaranteeing a leak-proof feeding experience. The lightweight and durable design of the rings mirrors the original Medela collars, making them easy to use and ensuring long-lasting performance. Made from safe materials and designed to be as functional as the originals, these rings can be used with both Medela plastic and glass bottles. To ensure your complete satisfaction, we offer a 30-day satisfaction guarantee: if you're not entirely happy with the replacement collar rings, we will provide a full refund with no questions asked. Please note - Pequeño is not associated with Medela or any other entity associated with Medela Holding AG Company.