Two stage cylinder?

Im a bit cloudy on what it is and whats it is soppose to do. Also how would ou pick the cylinder size?

It’s commonly used to describe a pump that pumps your dick and balls. For a much fuller description I suggest you do a google searchfor penis pumps and then see what is on offer, and a full description of what it is supposed to do. Rather than us give you details which you may not want.

Hope that helps.

It’s a cylinder with two separate diameter sizes and allows for much greater expansion of your ballsac. I would recommend the size:
3 1/4”(entry diameter) x 4”(inner diameter) x 9 “(length)