Our Transit Collection with AeroLight™ technology is engineered to be light, packable, and leakproof for the trail or the daily commute. Our commuter-friendly Transit Mugs are 33% lighter than Stanley’s standard stainless-steel metal drinkware. The collection is built with Stanley’s AeroLight™ technology, which consists of spun-steel, doublewall vacuum insulation to reduce weight—without compromising hot/cold retention or durability. These fully leakproof mugs offer a streamlined design and low-profile lid, compact and easy to carry. They also fit comfortably in car cup holders.AeroLight™ feather weight insulation Double-wall vacuum insulation 18/8 stainless steel; naturally BPA-free Leakproof Locking, drink-through lid Car cup holder compatible Dishwasher safe