Finis Snorkel Cardio Cap Designed specifically for the FINIS Original Swimmer's Snorkel (both adult and Jr). Should be used for hypoxic training to increases the ability of muscles to work better when oxygen levels are low. Improves breathing by teaching a deeper technique for high anxiety and race day environment. Replicates higher altitude workouts by increasing the amount of red blood cells and hemoglobin. Increases lung workout load by 40%.