Spill-Proof Silicone Accessory Set for Stanley Cups - Includes Straw Covers, Round and Square Leak Stoppers - Anti-Dust Tumbler Accessories

Works very well with a 40 ounce steel cup from Spencer stores. This cup I used also has a turn around to close part like Stanley has. I did get the straws and cup boots too. No leaks. I will say even if you don't have a Stanley cup it was worth buying the accessories. I am very happy with this product.

Pros:AffordableDoes exactly what it says it doesComes with a cute lil container to store the extra piecesCons:No instructions , design is intuitive but a reference would be helpfulThe circle stopper fell off twice after putting it on - however it did not cause leakageOverall happy with this product but annoyed that the cup didn't come with these features already.

Every time when I refilled my water and drank out of it from the straw , the middle round part always came off and dropped inside my water. I don’t know why really. I thought I didn’t put it in the right way, but it happened so many times after I put it back in and it came off again. The straw part was excellent it didn’t leak at all, but that middle part is bothering me.

My daughter and I were disappointed with how much the Stanley cups leak. These nicely fit stoppers truly helps! My daughters 40oz doesn't leak at all, my 30 oz does maybe a driplet. Honestly, I'm nervous of tipping it over like my daughter does hers all willy nilly. I like the simplicity of the rubber and the top stopper seems like it can handle alot of putting and pulling off. Great product, great price.

Bought as a gift/stocking stuffer and went over very well. Everything fit nicely and worked as expected on the Stanley.

the stoppers are really cool. only thing we don't like is the limited vacuum it has which is expected. the bigger piece falls off here and there during drinking. just lands in your water which is kind of funny to me. without the bigger piece, water will spill out. it was easy to put on without instructions. i just personally don't like when i want to take bigger gulps, it limits how much i drink, considering that my stanley (40oz) is my go to gym cup.

Sizing was perfect and leak proof was nothing less than amazing. Durability could be a bit better but other than that there’s nothing wrong with this product. Definitely worth the money

Fits my 40 oz Stanley great. It no longer leaks. Only draw back is the small cap inside the lids constantly falls off. I don’t use it but it still doesn’t leak.