Features Strength training for inhale and exhale breathing. Independently adjustable inhale and exhale controls. Hand grip for comfortable use. Detailed user instructions for proper training. The PowerLung Sport was designed for high performance athletes and has the highest resistance of the PowerLung Active Series. This model is especially recommended for anyone involved in a sport that requires breath control. Regardless of the sport or activity you engage in, all aspects of your performance are limited by your breathing function. The PowerLung Sport is proven to work the 12 sets of muscles used for breathing and significantly improve lung capacity and performance. Every PowerLung Includes User Guide Booklet, User Guide DVD-Video, Zipper Carrying Case, and Product Registration Card. Manufacturer Warranty. The PowerLung Sport model is best for improving lung performance for activities such as: Cycling SCUBA Free Diving Firefighting Rowing Running Soccer Strength Training Conditioning Swimming Track Field Triathlon Independent studies demonstrate that PowerLung increases respiratory muscle strength for both inhale and exhale. These studies have documented the following: More than 40% increases in inhale muscle power. More than 150% increases in exhale muscle power. More than 25% increases in tidal volume. More than 20% increases in peak exhalation. Please contact us for references and/or copies of these studies and more. Advantages of using PowerLung: Strengthen respiratory muscles Increase lung capacity Higher aerobic capacity Improved Endurance Lower Respiratory Rate Lower Cardiac Rate Stronger Core Body Muscles