The West Loop Thermal Mug has an ergonomic shape and offers the high quality that you would expect from Contigo drinkware. It has the patented Autoseal technology, which makes the mug 100% spill proof and leaf proof. Simply press the button to sip from the cup and release to seal. The double-wall design has stainless steel inside and out, with vacuum insulated technology to keep beverages hot for up to 4 hours and cold for 12 hours. 470ml capacity. BPA free.