Kit Contents: 2 Flanges ( 24mm), 2 Duckbill Valves, 2 Backflow Protectors, 2 Tubes, 2 Bottles (with One-Piece Travel Cap). Compatible with Spectra S2, Spectra S1, Spectra 9 Plus Breastpump. Nipples and Dome Caps are NOT included in this kit Compatible and interchangeable with Spectra pump parts. Same suction power as OEM parts. Replace Spectra Flanges, Spectra Duckbill Valves, Spectra Backflow Protectors, Spectra Tubings, Spectra Bottles (Wide Mouth). Multiple flange sizes available: 15mm, 17mm, 19mm, 21mm, 24mm, 25mm, 27mm, 28mm, 30mm, 32mm