Sterile, pre-assembled and ready to use, reducing setup time. Proven Airlock Protection prevents air flow between expressed milk and tubing while pumping. Pumps directly into any standard-thread bottle or milk freezer bag to reduce the risk of contamination from milk transfer. Kit includes tubing adapter, two silicone tubing, two adapter caps, two silicone diaphragms, two 25-mm flanges, four white valves and two 4-ounce bottles.