We purchased the thermos and sippy cup at the same time. I really wanted to like both items, but they leak way too much. The thermos fell over on it's side the other day (noone noticed) and it made a huge puddle on the floor. It does do a great job at keeping liquids cold and my daughter loves the easy push button top (took her only 1-2 tries to figure it out). But, Thermos needs to do a better job on the leaking issue especially if they are claiming it's leak proof.