CONTENTS: 2 Shields (19 mm), 2 Wide-mouth Connectors. 19 mm shield is suitable for mothers with nipple diameter 17-18 mm AFTER pumping. The shield and connector constitute a breast pump flange. This set works for double pumping. FEATURES: Separable TWO-PIECE flange for Spectra pump, NOT like one-piece Spectra flange. Made by Maymom. Two-piece construction is preferable for easy assembly, disassembly and cleaning. It also fits most hands-free pumping bra on the market and home-made bra. Available shield sizes: 10mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm, 24mm, 27mm, 28mm, 30mm, 32mm, 34mm, and 36 mm. COMPATIBILITY: This set is compatible with Spectra Pump S1, Spectra S2, Spectra 9 Plus. Compatible ONLY with widemouth (wide-neck) bottle, like Spectra wide-neck bottle, Avent bottle, Maymom widemouth bottle. They are NOT compatible with OTHER widemouth bottles. To make it compatible with Medela bottles, try Maymom 3rd Gen Bottle Converter (Amazon ASIN: B07MGSNJYJ). REGULATIONS: All parts that come in contact with breast milk are BPA/DEHP free. Made by a US FDA inspected company, Maymom. Refer to her online access for test reports. Dishwasher top rack safe; steam safe sterilization. RETAIL POLY-BAG PACKED; sealed by the manufacturer, Maymom. NOT original Spectra flange, NOT original Spectra pump parts. NOT original Spectra S2 Accessories. NOT original Spectra S1 accessories. Products made by Maymom for Spectra users, not OEM parts. Compatible with Spectra S1, Spectra S2, Spectra 9 Plus pumps. It is acknowledged that flange (breastshield) size plays an essential role in pumping comfort and efficiency. Maymom develops 11 sizes of shields to fit the average mothers and those in need of special sizes (e.g. 13, 15, 17mm). Maymom shield size refers to the INTERNAL DIAMETER (ID) at the ENTRY point of the tunnel where the nipple will go. For pumping comfort, measure your nipple diameter AFTER a pumping session, and then use the size selector of this listing to choose the size that is 1-2 mm LARGER than your nipple diameter as a starting point. Unfortunately, the best fit will never be discovered until you really try it out. That's why the two piece design is more economical for you to find the RIGHT fit. Improvements of Maymom Two -Piece separable flanges over original Spectra flanges- 1. Easy Switch When Sizing This flange is made of a separable shield and a wide-base connector. With the Maymom wide-mouth connector, you can easily switch to most comfortably fitted shields. Available shield size: 13,15,17,19, 21,23,24,25,27,28,30,32mm. 2. Easy to assemble and disassemble Easy detachment makes cleaning a breeze. 3. Use with hands free pumping bra Examples __Simple Wishes __Madela Bra __Pump Strap __Momcozy __Pacasso __Bravado Contents Wide-Mouth Connector x2 ShieldX2 Duckbill Valve x2 NOTE: Collection bottles, backflow protectors and tubes are NOTincluded in this listing. About Maymom Maymom is specialized in developing breast pump parts that can work with many name brand pumps on the market. The value of Maymom is to care for each mom! Disclaimer: Maymom is an independent company. Spectra is a trademark of Uzinmedicare, Korea. Maymom is not affiliated with Uzinmedicare.