The 350 ml Stanley AeroLight double-walled transit tumbler with vacuum insulation is designed to be lightweight without compromising the desired liquid temperature, keeping drinks hot for 6 hours or cold for 8 hours. The tumbler is leakproof with a locking screw-top lid. This means you do not have to worry about spills as you throw your bottle in your bag and jump on your commuter train or begin your exercise. In addition, the AeroLight tumbler is dishwasher safe and BPA free, and is designed for easy cleaning. Fits most car cup holders. The commuter-friendly transit tumblers are 33% lighter than Stanley’s standard stainless steel drinkware.