Compatibility:Compatible with eufy Breast Pump E10 / E20 / S1 / S1 Pro. Closed, Anti-Blackflow Design: Designed to prevent backflow of breast milk and help direct milk to the bottom of the container, ensuring no loss of suction. The slit on the valve tips remains closed when not pumping. Food-Grade Silicone: Made from durable, BPA-free, food-grade silicone, the duckbill valves are soft, odorless, and skin-friendly for both mother and baby. The snug fit offers comfort and efficient pumping. Easy to Clean: Wash with warm, soapy water and rinse well after each use. To deep clean, use boiling water or steam at no more than 100℃ (212℉) for 5-10 minutes. Avoid hard brushes; use fingertips instead. Guaranteed Reliability: eufy breast pump accessories are covered by a 90-day limited manufacturer's warranty. Lifespan: Typically lasts 1-3 months. Replace if suction and performance decrease with use and sterilization, or based on your usage.