This plug is secure, sterile, and self-lubing, but, other than that, when equipped, its physical properties vary wildly. Its length, diameter, shape, and texture randomize themselves roughly once every ten seconds, and these changes can even include vibration, temperature change, and mild electrical stimulation. Caution - this item is to be used for supervised training sessions only - prolonged use will render the wearer unused to a lack of stimulation, and when their ass is at rest and unfilled, they will feel as though something is wrong, and that they need something, anything, to fill it.
Found in: Autonomous Items, Fillers, Vibrators