The CT Mask was designed specifically to give you the ability to breathe warm, moist air outdoors in cold weather. Inside each mask is a patented thermal exchange module which affects a heat exchange cycle regulating air flow through its chambers and directing the air over a low turbulence thermal medium. Heat and moisture from your exhaled breath is captured within the module and transferred into your next inhaled breath of fresh air, setting up a cycle of breathing warm, moist air. Even in freezing temperatures, you will breathe 80 degree air! Please note that respiratory masks are personal products which due to health standards may not be exchanged or returned for resale. Masks are guaranteed if defective in materials or construction.