CONTAINS 4 VALVES, 6 MEMBRANES, 2 PUMP-IN-STYLE TUBES AND 2 ONE-PIECE BREASTSHIELDS, 19 mm (small breastshield); Compatible with Medela Pump in style advanced pump. Not compatible with FreeStyle, Swing Maxi, Sonata, Harmony, Pump in Style with Maxflow Pro Pro+. This 19 mm shield is not for every mother. Measure your niple diameter first after a pumping session. Choose one that is 1-2 mm larger than your niple diameter ALL PARTS ARE INTERCHANGEABLE WITH MEDELA PUMP ACCESSORIES. (Medela breastshield, Medela tubing, Medela valve, and Medela membrane. Not original Medela pumpinstyle parts). This is a Maymom made product, not original Medela pump parts. Being one piece breastshield design, this kit can fit Simple Wishes hand free bra, but not every home-made or medela bra on the market. YOU GET ALL YOU NEED TO PUMP EXCEPT BOTTLES AND THE MAIN MOTOR. Bottles are not included. This kit is compatible with Medela bottles, narrow neck Dr. Brown bottles, compatible with Ameda bottles (narrow neck, not Mya). US FDA LISTED CLASS II MEDICAL DEVICE No. D192499. BPA FREE and DEHP FREE - safe to use and same suction as the original OEM pump kit. NICE BABY SHOWER GIFT - Nicely made and packaged in a carton box by Maymom. A Great gift for mother to be. 12 DIFFERENT BREASTSHIELD SIZES available for best pumping comfort. Refer to size chart in product photos. This product is made by Maymom, and is compatible with Medela pump parts. It is well known that using the correct breastshield size is important for your pumping comfort and optimal milk supply. Compatible to the OEM 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. 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.