The Klean Kanteen Wide Mouth 40 oz. stainless bottle has an extra wide opening, which is more than 2 inches in diameter for quick filling, pouring and cleaning. It is made from high quality, 18/8, food-grade stainless steel that's totally free of BPA and other toxins. A Loop-top screw cap uses BPA-free polypropylene on the outside and food-grade stainless steel on the inside so your water does not come into contact with plastic. The loop top lets you attach the bottle to a backpack or belt loop using a small, lightweight cordage or a biner of your choice (a biner does not come with the bottle). This bottle measures 8.625" tall by 3.5" wide, and fits nicely inside any cup or pot that fits over a Nalgene® bottle. Warning: Never freeze your Kanteen as it can cause serious damage and void the lifetime warranty. The Kanteen is not designed for hot liquids as it it single walled.