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″, inner circumference: 4.71″. Width/Diameter: 2.10″. Circumference: 6.60″.