Features: Made of super flexible silicone material, designed for comfort and ease of use, with grippy surfaces, portable and easy to carry. Adjustable resistance, you can adjust the pressure level of the lung breathing exerciser to suit you and find the right levels of resistance for your training. The lung trainer regulates the amount of air-volume you inhaled, trains your breathing muscles, and enhances your endurance during any sport or daily activity. Perfect for people who need higher physical activity and greater breathing capacity for running, swimming, gymnastics, martial arts and other outdoor activities. Thoughtful gift for anyone who wants larger lungs, perfect for COPD patients, athlete, and singers or people in poor physical conditions who are under lot of anxiety and pressure. Specifications: Material: Silicone Size: Approx. 10x5cm/3.93x1.96inch Color: Black, White(optional) Package Includes: 1x Lung Capacity Trainer note: Please allow 0-1cm error due to manual measurement. make sure you do not mind before you order. Please allow slight chromatic aberration due to different display resolutions.