Doc Johnson Novelties Optimale Men's Sexual Health and Wellness line. Optimize your experience with these silicone cock rings! The Optimale Thin C-Ring Set offers enhanced size and girth with three rings in 40mm, 45mm, and 50mm diameters. These rings are ultra-stretchable for easy use around the shaft or testicles, maintaining those long-lasting erections you have always dreamed of, and prolonging your ejaculation. Available in Black and Slate; phthalate-free silicone. Video. 18.