●【Idea Companion for Stanley Cup】 Are you still troubled by the leak of tumbler? Our spill stopper set is the best solution, it keeps your cup completely spill proof. ●【Spill-proof】The straw cover for stanley 40 oz head cover can prevent drinks from spilling from the strawkeeps dust out and keeps the straw clean; the round stopper improves the seal and ensures drinking air can get in,the square spill stopper can form a seal and fix the straw ●【Perfect fit】 for Stanley straw cover compatible with Stanley Cup 1.0 40oz/ 30oz.Fitted in the straw hole of the lid, it not only creates a seal but also holds the straw in place. ●【Square Spill Stopper Seal】for Stanley straw cover made of safe food grade silicone, BPA free, durable, reusable, environmentally friendly and non-toxic. with excellent heat resistance and sealing properties. ●【Reusable】The reusable spill stopper set is a suitable companion for the mug and is so practical that you can use it yourself or give it to your family or friends.