The Hydro Flask 40oz Wide Mouth Insulated Bottle is a bigger water bottle for bigger thirsts or longer adventures. With six more ounces than the usual standard of 32, the 18/8 pro grade stainless steel keeps a whole bunch of drink cold up to 24 hours. The wide mouth opening doesn't just make life easy when you're parched, but even hooks to most backcountry water filters when it's time for a refill. Included with the bottle is the wide flat cap, just unscrew when it's time to drink that tasty water. Features of the Hydro Flask 40oz Wide Mouth Insulated Bottle TempShield? Double Wall Vacuum Insulation Stays Hot up to 6 Hours Stays Cold up to 24 Hours BPA-Free Proprietary Powder Coat 18/8 Pro-Grade Stainless Steel Lifetime Warranty