For Extra Thick results, look no further than the Doc Johnson OptiMALE 45mm 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 silicone. Inner Diameter: 1.77 inches. Circumference: 7.9 inches. Width/Diameter: 2.5 inches.