​​Answer:  You need to measure your penis using the instructions below:


Why is cylinder sizing important?

Dr. Joel Kaplan developed different cylinder sizes to maintain a good vacuum seal while allowing enough room for maximum growth. Instead of using a “one size fits all” approach that is less effective, Dr. Kaplan decided to use the best options that will allow for faster and better growth.

Step 1: Find your shaft circumference measurement
Wrap a tape measure around the base of your penis while erect. If you do not have a tape measure, use a string to wrap around your penis and mark with a pen where the string intersects.

Step 2: Measure your shaft circumference
Take the string off of your penis. Line it up next to a ruler and mark the measurement in inches. This is your base circumference measurement.

Step 3: Find your head circumference measurement
Sometimes the penis will be bigger at the penis head than at the base of the shaft. To make sure the cylinder will be comfortable, it is recommended to measure the circumference of the penis head. Wrap another string around the thickest part of the penis head, and mark where the string meets.

Step 4: Measure your head circumference
Take the string off of your penis. Line it up next to a ruler and mark the measurement in inches. This is your penis head circumference measurement.

Step 5: Find your erect penis length
Our standard cylinders are 9” in length. In order to make sure you have room to grow, we need your erect penis length. Take a ruler, and line it up against your erect penis. Push the ruler a little bit against your stomach (about 1/2 inch). Measure your full length to the top of the penis head. That is your erect penis length.

If you are 7.5 inches long or longer, we recommend purchasing the 12 inch cylinders in place of our standard 9 inch cylinders. This will give you enough room to grow.

Our 12 inch cylinders are $30 extra, as they are custom made in small quantities and are not refundable or exchange-able.

Why is scrotum sizing important?

If you are using Dr. Kaplan’s Dual-Cylinder program, we will need your scrotum size.

Dr. Kaplan developed a dual cylinder enlargement program that exercises the penis in 2 different ways to maximize growth. The second expansion cylinder fits over both the penis and the scrotum.

In order to send you the appropriate sized cylinder, we need to have your scrotum size.

Find your scrotum size

While you are flaccid (not hard), take a look in the mirror at your penis and scrotum.

If your penis and testicles hangs at about the same length, then your scrotum size is “average”.
If your penis hangs longer than your testicles, your scrotum size is “small”.
If your testicles hang lower than your flaccid penis, your scrotum size is “large”.


Question: If I want to buy a penis pump, how do I know which one to get?