It allows for mutual penetration between two persons (or for double penetration of a single female, both anally and vaginally). They are often made to resemble a penis, although some are C-shaped or S-shaped for G-spot or P-spot stimulation. Dildos are generally made of silicone rubber, but can be made of other materials such as body safe metals such as titanium, stainless steel, aluminum, or glass.
The internal rolling is claimed to enhance orgasms. Ben Wa balls are hollow metal balls inserted vaginally which can be worn inside the vagina for extended periods of time.
