when you working out you need something extra to handle what you doing this mask can help you it has four different levels the beginners four thousand ft, intermediate eight thousand ft ,experience twelve thousand ft, and expert sixteen thousand ft it can increase lung capacity and increase physical stamina in running Walmart got it on sale fo $19.97 they selling fast i saw only three left on the shelf probably going to be more soon especially if you need more than one for your work out group and family members and if you own a small gym good product to have