Leakproof in Action. The NAV 22oz is our cup holder friendly, fully leakproof, triple-insulated, stainless steel tumbler that works with both hot and cold beverages. The double-threaded design allows for left or right-handed use, while BevLock™ Technology seals it tight to prevent spills and a magnetic closure to keep the lid open while you sip. Perfect for morning coffee, late-night cocktails, and every drink in between.