For Extra Thick results, look no further than the Doc Johnson Optimale 35mm 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. Dimensions inner diameter 1.5 inches, inner circumference 4.71 inches. Width, diameter 2.10 inches. Circumference 6.60 inches.