Review on CleverMade Medium-Sized Reusable Ice Packs - Long-Lasting And Convenient Solution For Insulated Coolers & Lunch Bags - Keep Your Food And Drinks Cold Without The Need For Ice - Set Of 4 by Robert Robertson

I have the bigger ones and then got these smaller ones. Great for big coolers and even lunch boxes. They come empty, with a gel powder inside. Use the funnel to fill them up with water, use the plug to seal it and then once the cap is on, it locks it and doesn't back off. They're not indestructible but the bag itself is thick and pretty heavy duty. Good life span too, out of the freezer.