The Erectus Magna Erection Ring from Sinclair Institute is designed to create pressure around the base of the penis to limit the amount of blood loss from the penis after an erection is acheived. Minimizing blood loss helps maintain maximum erection size and rigidity, and prolongs duration of erection. Each ring is specially desgined with a notch that allows for ejaculation. Package contains 3 assorted sizes with diameters of 1 ", 1.25", and 1.5". Just choose the best fit for you. Wash with soap and water after use and only use as directed.