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 small, medium, large, or x-large breast shields and flanges. All Spectra Breast Pump parts that come in contact with Breast Milk are BPA free. For use with Spectra S1, S2, S3 and 9 Plus Breast Pumps. Included: Two (2) Spectra Duckbill Valves. Weight : .050kg.