100% spill proof design, just push to drink! durable silicone seals are totally leak-proof, even with the removable cover open. Easy to clean - base and cap are removable for super-easy cleaning & are dishwasher safe! Modular design features interchangeable lids and bases that work with smaller 16.5oz bottles; perfect for school or shorter trips! Spring-loaded lid opens with one touch to keep out dust & debris