Toppik Hair Building Fibers are statically charged, microscopic keratin proteins that instantly blend with your existing hair to conceal thinning areas, the appearance of hair loss, the look of receding hairlines, and even sideburns. These natural fibers adhere to each existing hair shaft, making your hair look instantly thicker and fuller. They are designed to resist wind and light rain, providing a natural and undetectable solution for thinning hair throughout the day.