Perfectly Compatible Our 12 set straw caps have a diameter of 10mm (0.4in) and are designed to be perfectly compatible with the Stanley 40 oz/30 oz tumbler with handle, also for the simple modern 40 oz tumbler with straw. They fit all large-diameter long straws with a diameter of 9-11mm, but please confirm the size of your straw before purchasing the straw cover cap. Food Grade Material: Made of food grade silicone, these straw covers are durable, reusable, and easy to clean by hand or in the dishwasher. They're airtight and sealed, dustproof and splashproof, making them perfect for outdoor activities. Plus, they can help encourage children to drink more water. Cute Design and Practical: These straw toppers are not only stylish, but practical too. They effectively block dust and other foreign objects from entering your drink, without harming your body. And they look cute too! Easy to Carry: This portable straw lid kit is small and easy to carry, making it perfect for outdoor activities like walking, camping, and hiking.