The H2S No-Fog Clip fastens to your balaclava and forms around your nose to seal leakage of moisure-laden vapors through to your area of vision. The H2S No-fog Clip has tabs that fold over the upper edge of your fabric headwear and then "tapes" down to the top of the fabric. Put on the headwear and gently shape the clip to your nose and cheeks for a perfect fit. This seals the areas on either side of your nose, a primary cause of fogging problems.