Kink Lab Steel O-Rings 3 Pack. These nickel-plated steel cock rings have a completely rounded edge, and give the user a choice of three different diameters to ensure comfort. Great for experienced users, this pack allows the casual cock ring user to experiment with firmer materials and more intense sensations. This cock ring set is also ideal for using with women's harnesses that have an interchangeable O ring option. Also available in a rubber version, these fun and simple sex toys offer firmer, stronger erections. Color: Silver. Type: Cock Ring Set. Material: Nickel Plated Steel. Diameter: 1.5 inches, 1.75 inches, 2 inches.