CONTENTS: 2 XX Small 17mm FLANGES and 2 DUCKBILL VALVES for Spectra S1, S2 and 9 Plus breastpumps. ALL PARTS MADE BY NENESUPPLY. Not Original Spectra S2 Accessories. Replace Spectra S2 Flanges 17mm and Duckbill Valves. COMPATIBLE and INTERCHANGEABLE WITH ORIGINAL PUMP PARTS. Same suction power as OEM parts and S1 accessories. DUCKBILL VALVES EASY TO INSTALL AND REMOVE. DIFFERENT FLANGE SIZES AVAILABLE: 17mm, 19mm, 21mm, 24mm, 27mm, 30mm. MATERIALS DO NOT CONTAIN ANY BPA. Can be sanitized with water steam, boiling water or microwave-steam bags. Tested by independent labs for safety.