This size of flange is NOT for every mother. Please refer to the product listing for sizing guidance. Contains 2x 18mm Maymom widemouth flanges and 2x blue duckbill valves for Spectra S1 Plus, S2 Plus, 9 Plus, Syngergy Gold and Motiff Luna, Ameda Mya/ Mya Pro Pumps. Maymom flanges work with spectra wide mouth bottles, AVENT bottles, and Maymom wide mouth bottles. They are NOT compatible with OTHER wide mouth bottles. Maymom flanges are also compatible with Spectra duckbill valve and backflow protector. US FDA Registered Medical Device (No. D192499), Health Canada License (No.26003), Australian Health and Aged Care (ID 463470). Inspected by US FDA. Comply with FDA/EU regulations for plastic materials that contact food. Test reports are conducted by independent lab and available online for reference. Multiple flange sizes available: 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm, 24mm, 25mm, 27mm, 28mm, 30mm, 32mm. Made from BPA-free material. Can be cleaned with water steam, boiling water or microwave-steam bags. Retail packed, sealed by the manufacturer - Maymom, not Original Spectra parts. Maymom is not affiliated with Uzinmedicare, the trademark owner of Spectra. Maymom flange and BLUE valve compatible with spectra pump s1, s2 and synergy gold. also compatible with ameda mya and mya pro.