SureThik High Performance Hair Thickening Fibers are lightweight natural keratin fibers with a static charge to keep them locked in place. Wind, rain and sweat are no problem for SureThik. Whether you’re a man with thinning hair or a female that would like to touch up a few weak spots, SureThik Hair Fibers are a premium hair loss alternative to traditional hair fiber brands that use a much coarser fiber and contain artificial or unnatural looking materials such as rayon, bulky wool, cotton or a synthetics. With hairspray, these first-generation hair fibers looked adequate from a distance, but there were limitations.