Our Klean Kanteen Wide 40 oz water bottle is a favorite for backpackers and outdoor lovers due to it's large size, lightweight single-wall construction and wide mouth. The wide mouth fits most backcountry water filters for clean and safe water anywhere. The Loop Cap has a stainless steel inside so your favorite beverage never touches plastic. Compatible with all Klean Kanteen wide mouth caps including our Cafe Cap when you need a drink through function.