For Extra Thick results, look no further than the Doc Johnson’s OptiMale 40mm C-Ring! Made of soft, stretchable silicone for easy use around the shaft or testicles, these cock rings are perfectly suited for creating the most optimal of erections, and prolonging ejaculation. Phthalate-free. Men’s sexual health and wellness. Inner Diameter: 1.7″, Inner Circumference: 5.33″. Width/diameter: 2.30″. Circumference: 7.20″.