Spill Stopper Set for Stanley Cup 2.0 40oz 30oz, Accessories Including Straw Cover Cap, Fix Leak Stopper and Lid Spill Plug, Clear

I tested this product on my Stanley by filling it up and flipping it upside down and it worked!!!! No more leakage. Easy installation and dishwasher safe :) I definitely plan on purchasing more in the future.

These things are a game changer - make sure you are purchasing the correct set for your style cup. My daughter and I both have the 2.0 version 40oz. We use them for sports and for tournament travel. My daughter had problems as her cup kept getting knocked over by volleyballs and her cup would spill. I had issues as I would place the cups under my seat at tournaments and then continuously knock them over, thus spilling the water. These spill stoppers are a game changer and prevent leaks!Here are my notes from using them as I almost gave up on them.1. They do seem expensive for what they are but, I get it (shipping and convenience). However, I do like the fact that they include two sets which makes it a good value in my book.2. They are advertised as BPA free!3. The sort of rectangular gasket for the straw hole can be a bit hard to get on and almost doesn't seem like it will fit. If you keep working it, it does go on and fit our cups perfectly. One of ours went on super easy, the second one we had to just keep working around the edges with our fingers to get it to go into place.4. Problems with suction? I had them and was about to give up on this product. However, my daughter said hers was working perfectly which made me investigate a little further. I was having issues with the center gasket round piece. The first time I used it, it fell off into my water. Luckily, it is not big enough to suck up through the straw. After placing it back on suction was awful so I just removed it completely. However, this piece has a small x cut in the center. I found that the rubber was not cut all the way through. I used my finger to push on the area and open it up. After doing this the suction is back to normal and this product is working great!No more spills - my daughter and I are both very pleased!

The color is perfect and can’t see it through the lid. The suction is just enough for it to not leak. Very easy to use in my opinion. Super durable. Easy to clean and wash. Great value for money.

It is very good at stopping the Stanley from leaking and it’s pretty easy to put on, only thing is that it’s not reliable. If the cup gets in the right position it will leak not much maybe like a couple drops but it does leak. It also could just be user error. Pulling the straw doesn’t wedge it out of place so it stays there really good after you put it on.

Did exactly what I wanted it to do! Keeps my Stanly cup from leaking when falling over!

Worked great for my Stanley and helped prevent leaking.

I recently bought a holder for my Stanley, and it kept spilling water everywhere. I couldn't find a BPA free option until now. It was a little tricky to install, but once installed, you don't have to take it out, even when washing it. I have recommended this to all my friends and I will recommend it to you!

Update: it is not 100% leakproof if holding it upside down. It is leakproof laying down though.I was about to buy a whole new tumbler because of my Stanley leaking, but then I came across these! No leakage, affordable, and I’m still able to use my lid normally.