Vital capacity (VC) refers to the total amount of air that can be exhaled at once after inhalation. For adult men, the vital capacity is approximately 3500-4000 milliliters, while for women, it is around 2500-3000 milliliters. Generally, better health corresponds to a greater vital capacity. A spirometer is a portable, handheld device that measures your lung exhalation ability and provides accurate data reflecting tracheal ventilation. The significance of vital capacity: The lung's vital capacity is closely linked to human respiration. Physiological research indicates that low spirometry values compared to normal indicate potential oxygen supply issues within the body. During situations where the body requires increased oxygen—such as prolonged learning, work, or intense physical activity—oxygen supply shortages can result, leading to symptoms like headache, dizziness, chest tightness, fatigue, lack of focus, memory loss, and insomnia. These impacts can hinder both learning and work and may have lasting detrimental effects on health. Usage method: 1. Move the red movable buoy to the starting point. 2. Seal your mouth around the blue mouthpiece, take a deep breath, hold it, and exhale forcefully to move the buoy further. 3. Observe the buoy’s position on the scale. The average peak flow rate for adult men can reach 400L/min, while women can reach 350L/min, and athletes can range from 600-700L/min. (Values are typically calculated in milliliters. This lung activity meter measures in liters. Conversion: for a measurement of 400L/min, the equivalent in standard units is 4000ml/min.) Instructions for using the peak flow meter: Position the red dial to the starting point, ensuring that your fingers do not impede the dial's movement. Stand upright, take a deep breath, and place the mouthpiece in your mouth, ensuring a tight seal. Exhale forcefully and quickly. Record the value indicated by the red pointer, reset it to the starting point, and repeat this process three times, noting the highest value. Key points to remember: exhale with maximum effort and speed; ensure lips are tightly around the mouthpiece to prevent leaks; do not obstruct the opening with your tongue. If retesting is required, remember to reset the red cursor to the lowest point before each test. Package includes: 1 Spirometer (suitable for adults or children, color may vary). When making a purchase, please be mindful of the product’s size and dimensions to ensure it meets your requirements. Detailed information about the product, including features and specifications, is provided in the title and description. We strive for your complete satisfaction with your purchase. If you have any questions or concerns, please feel free to reach out to us. We're here to assist you and will make every effort to help. Thank you for choosing our product. We hope you enjoy it!