Cirkul All-Day StrawSip™ Adapter Lid & 2 Flavor Cartridges, Leak-Resistant Lid with Reusable Straw, Compatible with Most 40oz. Tumblers

I love it. It fits and functions perfectly in my off brand 40oz tumbler. I wished there was an option to pick different flavors, but all in all it's good for the cost. And the flavor on the strawsip is strong without getting the mouthful of straight flavoring that you get when you have to tilt the bottle. The quality of the product is good and it's really easy to use.

I love the design works great and easy to assemble.

This did not fit any Tumbler I had and I tried so many brands. I reached out to Amazon customer service and they said it was not returnable. I have no idea why because it is not a food product they would make no exceptions but outside of the Amazon issue. The product itself was useless Because it doesn’t fit, which is the point of getting this. It’s supposed to convert any Tumbler into their compatible product.

Works well, only fits Stanley brand.

This attachment works great with my Stanley cups! I love that you don’t have to tip it like with regular water bottles. The flavor comes through easily as you drink. It screws on tightly and fits the top well, so there are no leaks. You can also adjust the dial to set the flavor strength to your liking, which is a really nice feature. It is a clear colored lid, so it will match any cup. Cirkul offers a wide variety of flavors, so you can pick whatever you enjoy most. This set even came with two flavors to start with, which was perfect for trying it out. The price is affordable. The flavor is strong and refreshing, and overall this attachment makes drinking water more fun and customizable. I haven’t tested it on other tumbler brands, so I can’t say if it fits all of them, but it’s perfect for my Stanleys.

This adapter lid changes the game for water tumbler users. It fits snugly on most 40 oz tumblers, and the reusable straw stays put—even when it's in your bag. The lid is leak-resistant, so I can toss it in my backpack or cupholder without fear of a mess. The flavor cartridges are easy to insert and offer a nice flavor boost—just squeeze or sip to adjust intensity. I tried both included flavors and appreciated being able to do light to strong depending on my mood. Plus, it keeps me drinking plain water more often, which is a win in my book. Cleanup is simple—lid pops apart, straw detaches, and everything rinses out quickly. Great for daily use, gym sessions, road trips, or desk days. No more flavor packets gunking up the bottom of your bottle. Just pop in a flavor and go.

So this cirkul adapter really only works with the name brand 40oz tumblers and close dupes. It has to be the same dimensions for the lid and screw top. I have one that is the same style but doesn't have a screw top lid and this did not fit. However, my other one that does have the screw top did fit it. So it just depends on which you have but make sure you check before ordering. It works well and if you've tried cirkul before then you know you can kind of adjust how much flavor you want. So I don't get those complaining about it being too strong or too light of flavor. It works well but just kind of adds an additional step to things and is kind of bulky. Personally I prefer to just use a cirkul water bottle for when I want that and then leave my 40oz tumbler for other things. However, that is a personal preference and this is exactly as described and pictured so 5 stars.

the top of my cirkul sip bottle fell and broke and i ordered this replacement but unfortunately it dosen't fit the cirkul bottle I already have. I already used the flavor cartridges in my other bottle so I can't return. otherwise it looks like its well made