Far-infrared fibers, and components and uses of the same are provided. The far-infrared fibers can be used together with other optional fibers to provide a product containing far-infrared fibers. The product does not emit harmful radiation and could raise a user's body temperature safely to increase the volume and rate of the user's blood flow without affecting the blood pressure and pulse of the user. Furthermore, the product can be male underpants that can improve male sexual function without affecting the physiological state.