6pcs Silicone Spill Proof Stopper Set, Reusable Leakproof Plug Spill Proof Straw Stopper with Straw Covers Seal Tumbler Accessory Compatible with Stanley Cup 2.0 40/30oz (Cream Yellow)

Seriously, not a single drop leaked!! I just put the parts in my tumbler and tested them by shaking the Stanley quencher upside down over the sink and not a single drop fell Obviously it affects the flow of the water as air has to come in so you have to let go of the straw after each sip or two, but I don’t see this as an issue as I will mostly remove the middle part that goes inside the lid while using and place it back on when I need to put it in my back of the buggy’s basket. I’m actually astonished that Stanley hasn’t thought of selling these as an add on 🤯 Never mind! Cheap works for me 😂 and it’s really working!!!

Good item but does not do the job 100%.

I bought this for my Stanley cup and it actually stops it leaking! Totally recommend

Not leak proof but the straw part looks nice and fits the straw in my 30 ounce cup

I only actually use the part that goes around the straw (filling in most of that large gap), and find this stops water splashing up onto my Stanley's lid while driving. I would recommend not using the round piece that attaches to the bottom of the lid, as this creates a blockage for air, which means drinking through the straw becomes more difficult and noisy. This is still worth the purchase without using that bottom piece.

Works at significantly reducing the amount of water spilling over but if help directly upside down it still drips.

Too big, didnt sit on straw.

Does the job perfectly. Very happy.

Die Stanley Cups sind ein wenig undicht, wenn komplett gefüllt, ich mag das nicht. Diese Stöpsel lösen das Problem und zusätzlich versperren sie Getier den Weg in den Strohhalm. Sehr gute Anschaffung!

Funzionano alla perfezione, salvano zaino e borse.

These spill stopper sets work on my Stanley Cup 40oz. It doesn't leak anymore. Very handy. The only thing is that when you lock all the air out, the last bit of your drink is a bit difficult to get out. A simple solution is to take out the middle part.

Il y a du mieux, car moins thermos fuit moins, mais ce n'est pas parfait. De plus, le bouchons étanchéité (interne) tombe souvent dans le thermos à cause du vide d'air que ce fait.

These fit perfectly on my 30oz Stanley tumbler. They keep my cup from leaking when I’m trying to carry more than I should, super easy to clean, inexpensive, and don’t take away from my rose gold Stanley’s appearance at all. Definitely worth the buy!