Sturdy bottles made from high-grade material.Compatible with all Medela pumps.Tight, screw on lid keeps leaks at bay. BPA-free with polypropylene plastic to retain milk's nutritional benefits. Easy to maintain and reuse. 3 high-grade breast milk storage bottles. Each of the bottles have been designed so that milk can be pumped directly into the container. The bottles have been designed to fit Medela's container stand and are compatible with all of Medela's products. The bottles also contain easy-to-read measurements in both ounces and millimeters, making it easy for the user to keep track of the amount of liquid being stored in each bottle.