Firefly Halo 55mm e or approximately 2.16 inches Cock Ring Medium Blue. Firefly Halos are glow in the dark cock rings made of soft and stretchy silicone for a snug and comfortable fit, ensuring prolonged performance and enhanced climax. Available in assorted colors and sizes. Collect them all! Product dimensions 2.1 inches by 2.1 inches by 0.4 inch. Material Silicone.