Mossy Oak 30 oz Rover - Mammoth Coolers The Mammoth Rover tumbler is the ultimate way to take your favorite beverage on the go. The double-walled vacuum insulation keeps your beverage the perfect temperature, with no condensation. The Rover tumbler is built with 18/8 kitchen grade stainless steel making it durable and it will not leave a metal flavor. With a crystal clear lid, rubber gasket and rubber stopper your beverage will maintain constant temperature longer, making ...