Regain Thickening Hair Fibers by Absolute New York are hair fibers that can be used to conceal thinning hair and create a fuller, thicker head of hair. The fibers are designed to match the user's hair color and bond with their own hair to create a more natural look. The fibers are safe, secure, and undetectable up to two inches away. They can be used on clean, dry hair and will stay in place all day and night, even in rain, wind, and perspiration.