Nailner Pen is can prevent nail fungus and infections. The handy pen allows an easy and quick application. Each pen contains approximately 400 single applications. By saturating the keratin layer of the nail and lowering the pH of the infected nail, Nailner products create an unfavorable environment to the disadvantage of the fungus, thereby treating Onychomycosis. See visible improvement after only 2 weeks of treatment. Please note that results may vary. . Please note that results may vary.