The Spectra Duckbill Valve Set is designed to increase suction and provide better output during breast pumping sessions while preventing backflow contamination. Each duckbill valve is one-piece making it easier to clean and lasts longer. Spectra Duckbill Valves are made of silicone and quality tested to ensure a sturdy grip on Spectra flanges. All Spectra Breast Pump parts that come in contact with Breast Milk are BPA free.