Breast Pump Valves, Compatible With S18/s21 Wearable Pumps, 4-pack Replacement. Wearable Breast Pump Accessories Enhance Your Breastfeeding Experience with These Essential Replacement Parts for Breast Pumps S18/S21. Crafted from Food-grade Silicone, These BPA-free Accessories Are Safe, Soft, and Odorless, Ensuring Peace of Mind for You and Your Baby. Designed for Easy Installation and Cleaning, Simply Wash with Warm Soapy Water After Each Use for Optimal Hygiene. Improve Efficiency with This Breast Pump Milk Collector Cup Replacement Kit, Thoughtfully Created to Support Your Needs. To Maintain Optimal Performance, It's Recommended to Replace Parts Every 3 Months, Ensuring Consistent Suction and Effectiveness. Features: - Compatible with Breast Pumps S18/S21 - Made from Food-grade Silicone, BPA-free - Easy to Install and Clean - Enhances Pump Efficiency - Recommended Replacement Every 3 Months for Best Performance.