First off, let me say this silicone divider is a game-changer for my 40oz Stanley tumbler. The cream/light green combo looks chic, and the food-grade silicone feels premium—no weird smells or flimsiness. It survived my brutal dishwasher tests and didn’t warp after holding icy smoothies and hot coffee simultaneously.

But here’s the real tea: those included lids? Trash. They wobble like a Jenga tower and don’t fit under the tumbler’s main lid. I gave up after the third time my iced latte sprayed everywhere while adjusting the straw alignment. Pro tip: Ditch the lids and use the divider bare—it’s way less fuss.

The compartment size is perfect for my weird habit of mixing coconut water (left side) and cold brew (right side), though you do sacrifice about 10oz of total capacity. Worth it for no flavor cross-contamination during hikes!

Wishlist: A version with tapered edges to reduce liquid loss, and maybe color-coded straw holes. Still, for $18, it’s a solid upgrade if you’re a serial beverage switcher like me.