Trade with the awesome DanielKay DanielKay
 
It’s a clear plastic tube, the penis inside is suspended by a few rubber rings that are connected by elastic bands to the outside of the tube, maybe 3 rings along the length… a thin catheter is inserted into the tip of the penis allowing urinating but nothing else.
 
The tube is under a slight vacuum forcing the penis to always be erect and giving the permanent feeling of being “sucked”, also constantly keeping the wearer on the edge… but since there’s almost no transfer of sensations from the tube to the penis there’s no way to get off.
 
The balls could are encased similarly, though here instead of a vacuum they are encased in a thick liquid which oppositely is under pressure, constantly giving them a squeeze while the shell can accommodate to them swelling.
 
Basically the only way the wearer could get off is by anal penetration, but that could be prevented by a “no entry” sign on an one way valving plug.