STOP YOUR STANLEY FROM SPILLING! The biggest problem with the Stanley Tumbler is it spills. Introducing the Stanley Tumbler Spill Stopper, the perfect accessory for your Stanley 40oz Tumbler. This innovative spill stopper will keep your drinks contained, making it the ideal companion for everyday activities or long commutes. Whether you're sipping coffee, tea or your favorite beverage, the spill stopper will keep it safe and secure. Made from high-quality materials, it is designed to fit snugly on the Stanley cup and will not leak.