Cock Rings. These rubber donut-shaped devices tightly encircle the erect penis. Typically used to help maintain erection, they also provide a small--temporary--size boost. Flaccid or erect, blood circulates in and out of the penis. One of the veins that carries blood out runs close to the organ's skin (on top). A ring restricts outflow somewhat by compressing this vein. Don't expect miracles. Any effect is modest and temporary.
“I have personally recommended this to men and I have received lots of great feedback regarding its long(er) term use. It’s a hydropump, so it works by using water when you’re in the shower or bathtub. To fully understand this, it’s important to know that the penis has three soft chambers, the corpora cavernosa (two large one’s on the top of the penis) and the Carpus Spongiosum (a smaller one on the bottom of the two). When these two fill with blood, you get an erection. What Bathmate or a penis pump can do is expand these chambers, thereby allowing more blood to fill in."