Review on Tommee Tippee 'Sippee' Toddler Sippy Cup: Spill-Proof, BPA-Free – 9+ Months (3 Count Pack Of 1) by Linda Peoples

I know a lot of the negative reviews talk about it not being leak-proof, but I really had no issues with that. I lined up the silicone valve with the plastic valve, making sure those parts were secure first. Then I pushed them into the slot on the lid. I'm not sure if others are trying to put those pieces on the lid separately (I say that because my husband did this and caused it to leak everywhere), because that will definitely make it harder to secure them.Anyway, my issue with this bottle is mold! I expected the 2 valve pieces to mold if left unclean for a few days, those pieces can easily hold moisture in-between. So I was very diligent about making sure the cups were cleaned well every day.However, what I didn't expect was the cup itself to start molding! This morning I pulled one of the cups out of the cabinet and noticed spots of black mold inside. I think the problem is the shape. It's difficult to get into the cup to get it fully dry, and air drying doesn't seem to do anything. So unless you want to constantly spend time cleaning and FULLY drying these cups, I wouldn't bother!Our daughter has also been using the Munchkin 360 sippy cup, and I would say that one is leak-proof enough (if it sits knocked over on the ground for an extended period of time, it will leak out a little), has less parts to deal with, and has the added benefit of helping teach her to use a proper cup. I think we'll start using that one exclusively now.