A "cock ring" is a constriction device that is placed around the penis alone, around both the penis and scrotum, or around the scrotum alone ("testicle cuff"). Its aim is to restrict the flow of blood from the penis or scrotum to make an erection last longer. They are also called "tension rings" and "erection rings." They can help men who battle performance anxiety and erectile dysfunction. Metal rings are typically considered safer than elastic rings.