6Pcs Spill Proof Stopper Silicone for Stanley Cup 2.0 40oz/30oz Tumbler Leakproof Water Bottle Sealing Accessories with Round Top Leak Proof stopper Plug &Square lid anti-leak Stopper&Straw Cap Cover

I really liked this product because it allows me to carry my older Stanleys (I think they had prettier colors back in the day: Cloud, Alabaster, Petal) without having to worry about my items getting wet when I tilt the bottle. I think the price is pretty good considering you get two sets so you can use it for two bottles.

great product, does make my stanley leakproof, but it does make the suction a little weird, but its not bad, just depends if thats a pet peeve of yours. Besides that for the price its nice!

Works as leak proof as long as straw is in place. If straw is removed and cup is turned upside down, the Stanley cup is not leak proof. I’ll leave my straw in place and it will be leakproof. The suction function does require more effort when drinking out of it versus not having the attachment.

I've had these stoppers for a month and so far no issues! I use them for both of my Stanley cups and I lovee them! No leaks except from the straw when in use. Game changers!

I struggled with the plug for the straw as it has to be tight to be leakproof. Once all the plugs were installed, I have no worries about spills or leaks.

This product does what it says it will do. It makes your Stanley Cup leak proof! As a result your sips will be smaller from the straw though, because that’s how suction works. It’s a trade off of air. I can’t knock off stars for that. Investigating now which piece removed from the equation results in the least leakage, will update with findings.

I have a Stanley Cup 2.0 40 ounce which leaks a lot if tipped over. This product is of no value.

Not stanley but will try to see if it will keep my cup from spilling

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Purchased this for my partner and it really helps prevent leakages from the Stanley cup itself, easy to clean and use as well

I wish these came with instructions for each part. I was able to put down 2/3 from them. The third, I wasn’t sure what it was for. Doesn’t stop the spill, but again, maybe it’s because I didn’t know what to do with the third piece.

If you have a Stanley you need this! Stopped all the leaking.

If you have a Stanley Cup this is a necessity. My Stanley always leaks but with this set not one drop. Absolute must have.