Best Choice for Breathing Training This latest upgraded oxy flow breathing trainer is the best assistant for everyone who desires to enhance respiratory muscle endurance and diaphragm expansion through breathing training. No matter you are in any life scene or doing fitness exercises, you can easily use it at any time to improve your breathing function and maintain the best vitality. Customized Adjustable Resistanceoxyfit breathe trainer is designed with personalized resistance adjustment system. You can adjust the resistance by rotating left or right, easily find the resistance threshold that suits you and gradually improve the training effect. Every practice can make a difference for you! High Quality & Comfortable EnoughThe mouthpiece with integrated bite design provides a more natural fit during use.The high-quality silicone material ensures that it is comfortable enough for long-term bite training, and its durability is 2.5 times that of other ordinary breathing resistance trainers. Double Improved Training EffectAre you constantly striving to exceed your physical limits? The answer is here! Our breathing trainer is the best breathing exercise device for every sports enthusiast.It's perfect for physical training, running, swimming, track and field, cycling and many more high-energy activities. Double Improved the training effect will give you greater breathing capacity to achieve optimal sports performance. Scientific Breathing PracticeThis oxyfit breathing trainer is very easy to use. Just practice breathing exercises two or three times a day by repeating the pattern of deep breathing (nose) and slow exhalation (mouth) for 10-20 times in a row. According to test, after about 30 days of breathing training, You will have the strength to blow up astandard size balloon with one exhale.