Kit Contents: 2 Flanges ( 21 mm small flange), 2 Duckbill Valves, 2 Backflow Protectors, 2 Tubes, 2 Bottles (with One-Piece Travel Cap). Work with Spectra S2, Spectra S1, Spectra 9 Plus Breastpump. Interchangeable with Spectra pump parts.
eBay