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

Works better than I thought. Sometimes too good. You can't use the bigger piece and drink from the cup at the same time. If you are traveling you can use it but remove it to drink from it. It is leak proof. Great design. Easy to clean and fits perfectly.

Perfect to help keep your stanley cup spill proof. Perfect for any color stanley cups

I kept knocking my cup over and water was going everywhere.While these are not 100% leak proof, they definitely help with not losing at 40oz of water immediately and for the price it's not worth complaining. My spilling problem is now a few drops problem and I can live with that.

I got these for my grandaughters stanley mug. They work great for her

This product is tru to its word. It really does make the Stanley cup spill proof.

Perfect

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.

It fits the Stanley cup. It does prevents spills.