Feature: 1. 1. Efficient: Provides the widest range of inspiratory/expiratory resistance levels to meet anyone's needs. From the low resistance of respiratory rehabilitation patients, it gradually increases to the high resistance level of competitive athletes. Improve endurance, breath-holding and shortness of breath. 2. 2. Easy to use: only one moving part. Rotate the valves to the left to reduce airflow to create more resistance, and rotate it to the right to reduce resistance. 3. 3. Very compact, only 4" high: you can take it anywhere and use it anywhere (pocket size). Very comfortable. The flexible silicone mouthpiece is very comfortable and provides excellent fit and tightness. Once in your mouth, you won't even need to hold it with your hands. Highly durable, heavy-duty plastic construction and 100% rust-proof. 4. 4. Immediate benefits: It will open up airways that have been partially blocked due to natural aging, pollution, poor physical condition and smoking (if applicable) over the years. 5. 5. Long-term benefits: It will be aimed at and develop the respiratory muscles (diaphragm and intercostal muscles), helping you draw more air/oxygen into your lungs and exhale more carbon dioxide. Specification: Material: SiliconeSize: 10*5cm/3.9*1.9inchFunction: Simulate altitude training, adjustable intensity, improve cardiopulmonary breathing ability, and improve endurance Package List: 1*Breath Traine