Spectra Duckbill Valve Replacement Set of 2 Valves is compatible with the following breast pumps: Spectra S1, Spectra S2 & Spectra 9 Plus. Spectra recomments replacing the duckbill valve every 3-6 months. BPA/DEHP FREE: All of Spectra Baby USA storage containers and parts that come in contact with breast milk are BPA/DEHP free. Discounts for higher quantities.