LS Enhancing Adjustable Penis Ring

Adjustable diameters, wraps around the base of your penis, can also be wrapped around your testicles at the same time. Great looking cock restraint that improves erections for most people. These simple little liquid silicone restraints will bring you absolutely new sensations. 

How a cock ring can improve your sex quality? (healthline.com)

These sexual devices help trap blood in and around the penis to prevent it from flowing out during an erection.

This makes the penis tissue harder — and slightly bigger — for a longer period of time. It can also delay orgasm to result in a more intense climax.