The St. Andrew's Cross, Crux decussata, X-cross or saltire cross, is a common sight in BDSM dungeons because of its practicality and ease of manufacture. It typically provides restraining points for ankles, wrists, and waist, and is usually strongly attached to a wall.
Some saltires are attached to a central hinge, allowing the subject to be spun and inverted: see also bondage wheel.
The St. Andrew's Cross and the spanking bench are the most common pieces of BDSM furniture. The submissive may be attached to the cross with either the back or front facing the cross. Being restrained facing the cross is the position often used for whipping. Back to the cross is usually more of a bondage position or for sexual teasing.
The Cross may be purchased from BDSM companies, but many users make their own. Freestanding saltires have a frame which supports the cross. Some homemade freestanding crosses have a tendency to be unstable; a writhing subject can sometimes turn them over, so great caution needs to be exercised in their use. Some freestanding crosses include footrests that greatly improve safety and stability.