Some dildos are designed to be worn in a harness, sometimes called a strap-on harness or strap-on dildo, or to be worn inside the vagina (then called strapless dildo or "strapless strap-on dildo"), sometimes with externally-attached vibrating devices. Strap-on dildos may be double-ended, meant to be worn by users who want to experience vaginal or anal penetration while also penetrating a partner. They may also be used for anally penetrating men. If a female penetrates a male, the act is known as pegging.