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: 2, inner Circumference: 6.28. Width/Diameter: 2.5″. Circumference: 7.9″.