A cock ring is a ring worn around the penis, usually at the base. The primary purpose of wearing a cock ring is to restrict the flow of blood from the erect penis in order to produce a stronger erection or to maintain an erection for a longer period of time. Genital adornment is another purpose, as is repositioning the genitals to provide an enhanced appearance. Cock rings are also called C rings, penis rings or shaft rings. When used in cases of erectile dysfunction (ED) they are known by various other names, such as erection rings and tension rings.