Perfectly compatible：Cute straw cover perfectly fits for 9-10mm 0.35-0.4inch large size straws such as 40 oz / 30 oz tumblers straws. Food Grade Material：Our Silicone Straw Covers caps are made of high quality BPA-free silicone that is odorless, non-slip and easy to attach to the straw, which is safe and hygienic for you and your family's health,you can use it with confidence. Dust and leakage prevention: The straw topper for stanley cup can prevent unclean stuff entering into the straw, clean and sanitary, making drinking more reassuring. Perfect Gift：These great cup accessories. great novel gifts for your friends or family. After Sales：If you have any questions about this straw cover cap for stanley cup, please feel free to contact us, any questions will be replied within 12 hours. 9-10mm Straw cover perfectly fit for Stanley 40 oz / 30 oz tumbler straws