Adjustable Resistance : This respiratory lung exerciser comes with a rotary valve and adjustable resistance settings. Adjust the resistance strength by rotating it left to right to find the resistance that best suits your needs. You can easily adjust the device to your personal needs. Lightweight and Convenient : The portable lung breathing trainer measures 3.94 inches * 2.36 inches * 1.25 inches. The lightweight and compact size allows you to exercise anytime in your daily life. The design of the breathing trainer ensures convenience and comfort for daily use. Application Scenario : Our breathing trainer is suitable for sports such as track and field, running, swimming, gymnastics, martial arts and outdoor activities, which is a must-have for sports enthusiasts,. This well-built breathing trainer is dedicated to helping you achieve greater breathing capacity for optimal athletic performance. Product Function : With this breathing exerciser, you will be able to strengthen your workout for a long time. Perform simple breathing exercises two to three times a day. Use a pattern of seven continuous repetitions of inhalation and exhalation, each lasting two minutes. Effectively exercise respiratory muscles and enhance breathing endurance. Promise : You will get breathing trainer. If you are not sure if the product is right for you, please tell us through our store homepage "Ask a question" or support . If you are not satisfied with the product for any reason, please tell us and we will resolve the issue for you. We can even provide you with a new product - no questions asked!