Let s keep it simple: this tumbler doesn t leak. The silicone sipper spout has a built-in valve that stops water from flowing when no one is drinking so it s easy for children to quench their thirst but won t make a mess if the tumbler is tipped over. It s the perfect choice for active kids or young ones just graduating from sippy cups who aren t ready for an open-topped tumbler yet. The antimicrobial drinking spout helps prevent the spread of bacteria so you don t have to worry when you take this travel cup on the go and the 12-ounce tumbler is vacuum insulated to keep drinks cold and stop condensation from leaving water rings. The stainless steel is durable reusable and completely BPA free and shouldn t be microwaved. We recommend washing the tumbler by hand (to preserve the vacuum seal and keep the artwork bold and bright) but the lid can be disassembled and put in the top rack of the dishwasher for a quick and easy clean.