We discovered a better sippy cup for breastmilk. Foogo by Thermos distinguishes itself from the plastic masses by being an insulated sippy. Keeping breastmilk chilled helps it stay fresh and safe longer. Foogo uses double wall vacuum insulation for maximum cold temperature retention, keeping beverages cold for up to 6 hours. That's all we needed to know. We give extra credit for the clean stainless steel interior and exterior, the fact that it's dishwasher safe, and the nice ergonomic design. The Foogo line also includes a food jar and straw bottle. You can find retailers in your area here.