The devices used to immobilize a person by restraining their limbs, specifically the wrists and ankles.
Generally wooden devices used to hold and restraint a person's wrists, and ankles from free movement. These devices are based on the 'stocks' of earlier times, and can be most elaborate or simple in design.
Restraints can be the wood device itself, or be other devices used after a person's ankles and wrists are placed through openings in a solid material, such as wood.
There are three basic types of stocks.
Little Stocks are more mobile units constructed to simply immobilize the arms and legs while a person may rest on their back, or be standing, in a bent over position.
Box Stocks and Frame Stocks are meant more to be fixed. The larger being the Frame Stock. These units are mainly constructed of wood, and can allow for the head to be included in parts of the body being held immobile.
These devices have the purpose to enhance the bondage aspect, either through simply restricting the submissive's ability to move, while being engaged in sexual acts, or for the infliction of pain, such as birching, caning, paddling, and other assorted rituals.
In some instances, the submissive is kept in this device, and other dominants are then invited to participate in the ritualistic taunting, pain infliction, of the submissive.
Generally it is used as a means of restricting movement, for the administrating of some form of punishment. It is also a way of enforcing one's dominance over another.
These devices can be mounted in doorways, at the foot of a bed even.
Practice (Associated Acts): Use of such devices in public exhibitions, such as the Folsom Street Fair in San Francisco is used to provide both education of the BDSM Culture or Acts, but also is used to provide a form of punishment for a wayward submissive.
There are possible legal ramifications as well.
Use of these devices is also part of the 'role playing' that might be based on medieval role playing, or similar scenarios.
Form of punishment in Medieval times, and of public humiliation.