The Next Generation of Nalgene bottle is here. This bottle has 53 mm opening, making it right between their current wide mouth & narrow mouth. The cap features a molded in loop, providing a convenient spot to clip or a nice finger loop for simple, comfortable carrying. Graduations are molded right into the bottle. This bottles capacity is 24 ounces or 750 ml. The cap also has a soft touch material for easy gripping.