At these parties, BDSM can be publicly performed on a stage, or more privately in separate "dungeons". A reason for the relatively fast spread of this kind of event is the opportunity to use a wide range of "playing equipment", which in most apartments or houses is unavailable. Slings, St. Andrew's crosses (or similar restraining constructs), spanking benches, and punishing supports or cages are often made available. The problem of noise disturbance is also lessened at these events, while in the home setting many BDSM activities can be limited by this factor. In addition, such parties offer both exhibitionists and voyeurs a forum to indulge their inclinations without social criticism. Sexual intercourse is not permitted within most public BDSM play spaces or not often seen in others, because it is not the emphasis of this kind of play. In order to ensure the maximum safety and comfort for the participants, certain standards of behavior have evolved; these include aspects of courtesy, privacy, respect and safewords. Today BDSM parties are taking place in most of the larger cities in the Western world.