For the length, choose a pump that is 2-3 inches longer than your erect penis. For example, if your erect length is 7 inches, select a pump that is 9-10 inches in length.

For the diameter, allow at least 1/2 inch of extra space around your shaft. To measure, wrap a tape measure around the thickest part of your erect penis to find the circumference. Then, select a pump with a diameter about 1/2 inch larger than your penis’s diameter.