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

Fits my daughter’s 40oz Stanley tumbler perfectly. She loves Cirkul and was super excited about the flavors included. There was really helpful information inside the box, too. We assembled the straw and made sure not to overload the cup with ice, like it said. If you have a Stanley and love flavored water, buy this! Both of the flavors are sugar-free which is awesome.

This is such a cool way to try Cirkul without having to add yet another drinking cup to your kitchen. It works easily and seamlessly with my 40z name-brand cup. It does take some figuring out to adjust the amount of flavor that comes from the straw. The fruit punch flavor is pretty strong, so I keep it low. Even if you have it set to be all water, some flavoring will seep in, so it isn't precise by any means, but I like that you don't have to use the flavor full force. It's pretty cool that you can have mostly regular water and just switch it up if the feeling strikes you. It saves time and money on mixes, which I like.

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.

Didn't fit on any of my 40oz cups and it was "not eligible for return". Disappointed

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.

I've been curious about the Cirkul system for a while, and this starter kit with the All-Day StrawSip™ Adapter Lid was the perfect way to dive in. The concept is fantastic – being able to flavor my water on the go and control the intensity is a must for staying hydrated. I love that it's compatible with most 40oz tumblers, which means I can use my existing favorite cups.The adapter lid itself feels well made and the straw is convenient. The two included flavor cartridges were a nice bonus and offered a good introduction to the Cirkul taste profiles. I've definitely noticed myself drinking more water since I started using this.My only minor gripes are that sometimes getting the flavor dial just right takes a bit of fiddling, and the initial setup instructions could be a touch clearer. Also, while the cartridges are convenient, they do add up in cost over time. However, for the convenience and the ability to customize my hydration, these are minor issues.Overall, if you're looking for an easy and enjoyable way to drink more water, the Cirkul All-Day StrawSip™ system is definitely worth trying. It's a solid product with a lot of potential!

Very happy with this. I wanted to try it and see if it really was what everyone was raving about. I am especially happy that I can use this on on tumbler I already have, and it fits perfect. I like how you can adjust the flavor flow. Some days you want a hint of flavor, others you want big flavor and this allows you to do that. It makes staying hydrated easier. I can't wait to try other flavors. There are tons to try. Also, you dont need to tilt this like the other Cirkul, it come with a straw extension. Super easy to use to. Just twist on the lid, twist in the cartridge and you are ready to go.

We have a regular Cirkul bottle, so we’re excited to try this new version. It fits a 40oz brand name Stanley cup perfectly. You can adjust the intensity of the flavor, which I really like because I like my drinks on the weaker side. The Pink Refresher is REALLY good. Tastes like Starbucks pink drink. I will definitely buy that flavor again as it’s my new favorite. I’m not a huge fruit punch fan, but it tastes fine. This lid is easy to use and flavors are available everywhere. I love that it goes on an insulated cup since the cirkul bottle isn’t insulated.