This is a very fun water bottle. My 6yo son loves it, and I am fairly impressed with this product. The food grade silicone is very flexible and the cap when fully seated does not leak. The reason it does not leak is due to the slightly angled silicon seal that does not have any separation seam in it. Meaning the seal is 100% all the way around the cap and is one piece.I am a Professional Mechanical Engineer, and the material of the body is what I like about this water bottle. The material of this bottle is not tin, stainless steel, high-density polyethylene, and it is not polyethylene terephthalate. It is basic food grade silicone. The about this item states: “The temperature resistance is from -40 ° C to 230 ° C.” This is a great lightweight bottle that can endure some punishment. And over the years we have been through all of those mentioned materials for both of my kids water bottles, and they just do not last.When closed the spout makes this bottle airtight. And you can easily test that because you cannot expand or collapse this bottle unless the spout is completely open. And that equates to a leak proof spout. Collapsed, it holds a lot of water, but fully expanded… 580ml equals about 19.6 oz of fluid, which is more than enough to hold a standard 12oz bottle of water.And why not have fun with the design… Which is why my son has this attached to his backpack. [...]
