Improve your breathing and endurance with the Training Mask 2.0 Sleeve. This high altitude training mask has a size small sleeve and is designed to enhance your athletic performance. With its adjustable resistance settings, it allows you to simulate high altitude training and challenge your respiratory muscles. The sleeve fits snugly over the mask and comes in a sleek design that's perfect for any athlete. Whether you're training for a marathon or simply looking to improve your cardio, the Training Mask 2.0 Sleeve is the perfect tool to take your fitness to the next level.