I just tried out my new Flip-and-Go Stainless Mug and this is a great product. My favorite thing is that it wont leak or spill if it tips over. I filled it with hot coffee and turned it upside down and shook it and not a drop came out.  The lock also keeps it from opening accidentally. I wish it was dishwasher safe but that is not a big issue. It does keep hot drinks hot. I filled it with hot coffee four hours ago and it is still piping hot.