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: 1.5â  , inner circumference: 4.71â  . Width/Diameter: 2.10â  . Circumference: 6.60â  .