The basic function of the valve is to drain the water out of the polycarbonate tube. While the Black Pip can be locked and unlocked. Leave it locked when you fill the tube with water and unlock it when you start pumping.
In addition there is a Quick Release Valve useful when you want to remove the pump. You can do it quickly, just press to relieve pressure instantly.
The Pump Tube is made from medical-grade polycarbonate which is safe (Phthalates free) and able to withstand water pressure. You need to fill the Polycarbonate Tube with water before placing your penis, in the context of a penis pump, water replaces air.
Unlike usual, this time you have to pump water instead of air in the tube to create suction.
It's like a spring but Bellows Pump is made from silicon rubber material. When you press it to become flatter, it will try to return to its original shape when you release it.
You need to pull the penis pump towards the pubic bone to start the penile pumping process.
This pad is made of medical quality PVC material which is skin safe and removable. At the bottom of the Comfort Pad there is a silicone rubber. In the context of a water-based penis pump this is called a Chamfer, a key piece that can create a tight seal and prevent air from entering.
How a hydro pump creates suction in the context of a penis pump. When the pump is pressed against the pubic bone, water naturally exits through the valve due to the push. This condition causes the Bellow Pump to shorten and remember it's like a spring which will return to its original shape if there is no push.
Suction is created as the Bellow Pump is pulled back and the amount of water is reduced in the Polycarbonate Tube. The amount of water that comes out of the tube and how much the pump is pushed to pubic bone determines the suction power.
WebMD explains that the penis has a pair of blood vessels called the Corpora Cavernosa, shaped like a sponge that runs the length of the penis. When the penis is erect both fill with blood.
The suction created by the hydro pump helps draw more blood flow to the penis. This condition makes the penile tissue expand. In the end the size of the penis looks bigger because it is fully loaded.
At first the enlargement is temporary, but with regular use the penis tissue is trained to receive more blood flow.
This is a short answer to how Bathmate works, although this succinct represents all of it, long explanations may be difficult to understand in general.
Each user needs to adjust the size based on their erection. Not sure which one to choose? The size range will help you.