This bottle has 53 mm opening, making it right between our current wide mouth and narrow mouth. The cap features a molded in loop, providing a convienent 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. Features: • Made with Polycarbonate • Extremely durable • Resistant to staining • Resistant to retaining odors • Recommended for "extreme" adventures • Dishwasher Safe (top rack only) • Withstands temperatures from -135ºC (-211ºF) to 135ºC (275ºF) Recommended for: Gym, office, trail, wall, etc.