This product is made by Maymom, and not original Medela products. <p> It is well known that using the correct breastshield size is important for your pumping comfort and optimal milk supply. <p> Compared to Medela valve, our design of valve allows your precious milk to flow easier into the bottle. The pump in style replacement tubing set will fit Medela Pump in Style Original (sold before 2004) and Pump in Style Advanced Breastpump sold after July 2006. Maymom breastshields can be connected with Medela storage bottles and other standard-sized bottles like Gerber, Playtex and Ameda. They are 100% compatible with Medela valve and Medela membrane. <p> Disclaimer: Medela and Pump in style are registered trademarks of Medela Holding AG, Switzerland. Maymom is no affiliated with Medela nor dose Medela endorse this product.