Basically, any item of furniture, in which the submissive can be firmly tied to, or bound to, that exposes the buttocks in an upraised manner.
Any device, or furniture can be used, to bind the submissive, so their rear is fully exposed. This is generally to allow for whipping, paddling, of the buttocks.
Gym horses are suited, for a standing male, while chairs with or without arms are also good devices, and less expensive than custom made devices.
Any form of ass play, can be more readily enjoyed, when the submissive is tied in this manner, such as in facing a chair, bent over.
This form of bondage, is not restricted to flagellation or whipping, but also for asshole play, toy insertions, etc.