Kit contains three rings. #17, #18, and #19. Perfect Fit has developed the first cock ring sizing system designed to fit you without too much pull but with enough restriction to be truly effective. Features: Ring Number 17 1.7 inches in diameter, 5.3 inches circumference Ring Number 18 1.8 inches diameter, 5.7 circumference Ring Number 19 1.9 inches in diameter, 6 inches circumference.