Cardio Training Mask

rand New- Box Destroyed :( NEVER USED This was purchased, put away in a backpack and forgotten about... A high altitude training mask uses a multi-level resistance valve system which reduces the amount of air flow to the lungs, forcing you to take more focused, deeper breaths. The lungs are pushed to work the tiny air sacs in your lungs harder, which improves blood oxygen flow the training of breathing against resistance will aid you in using available oxygen more efficiently, increasing your lung capacity and cardio performance.