Don't Waste Your Money

This cup is advertised as leak-proof, but it is far from it. The stopper piece is so poorly designed, it doesn't even require jostling or dropping for it to come out of its little placement and cause the contents to pour out. I'm not just talking a leak, I'm meaning completely emptying the cup. Not only does the stopper fail constantly, it also has such a poor straw mechanism that, when the flip-top lid is slid into closed position, there is always liquid left in the outer part of the straw that gets pressed out during closing.
Overall, this product is horrible and I wish I had kept my receipt so I could get my money back. Total waste of $7-$8!