Workout mask to build endurance This altitude training mask is equipped with 2 levers that offer 4 levels of resistance each. We also include 3 interchangeable valves with 4 additional levels each for even more customization. 8 PCS Carbon filters are also included in this workout mask to protect your lungs from pollutants and dust. Start low and increase the air resistance gradually to give your respiratory muscles a full workout. Practising this method will help increase your lung capacity, allowing athletes of all trades to boost their endurance and strength. Whether you’re a cyclist, runner, hiker, swimmer, gymnast, or weightlifter, incorporating this mask into your fitness regimen can deliver high level results. BUY NOW and achieve your fitness goals with the SELMUEL altitude training mask!