Great idea but poorly put together. The silicone lid has this bad odor (which I don't feel comfortable using). The rim on the cup has opening which will build up molds over the time. Therefore, the price are not justified.Update:Company advised me to boil the cup. I did exactly that. I was able to remove the odor by adding Cinnamomum tamala and Cardamom Pods, Green. But what scares me away Once you boiling the cup. There were air bubble. The rim was sucking the water in. Sure water got trapped under the rim.. once you shake it you will hear the water move. That's exactly how the mold will get trap over time.Great idea but poorly implement. I wish they sealed the rim or no rim at all.