Diposable hat liners for the inside of all head wear. Hats, Hardhats, baseball hats, helmets, everything just peel off the back, stick it in and go. Will help prevent sweat from dripping into your face, onto your glasses, AND KEEP THE SWEAT LINE FROM APPEARING ON YOUR HAT. Store in temperatures under 95 degrees Fahrenheit to keep adhesive in best condition, replace Sweat Shield every 1-7 days. Recycle after use!