- The YETI Rambler 14 oz. Mug is the toughest, most over-engineered camp mug out there. Unlike traditional camp mugs, this double-wall vacuum-insulated body protects hands from hot or cold contents while keeping coffee, chili, oatmeal -- you name it - well-insulated. The mug"s wide opening means contents are easily accessible, but will cool quicker. That"s why the mug comes with the standard Rambler 30 oz. Lid (also compatible with the Rambler 30 oz. MagSlider Lid).