A glans ring with sperm stopper is a popular product for fetish and SM enthusiasts.
Pull the ring over your glans and insert the ball into the opening for the urethra. This creates a stopper for your penis, and you will not be able to ejaculate. The sensation is both titillating, painful and humiliating.
The ring is made of surgical stainless steel. It comes in three different sizes, with a diameter of 25 mm, 28 mm and 32 mm, respectively.