Ausführliche Antwort
From the outside, an implant is hidden. All parts sit inside the body.
Inflatable implant
In a three-piece inflatable implant, two cylinders sit inside the penis, a small pump sits in the scrotum, and a fluid reservoir sits in the lower belly. Squeezing the pump fills the cylinders and creates an erection. Pressing a release lets the penis go soft again.¹ When the device is deflated, the penis is soft and hangs naturally. When it is inflated, the penis is firm and erect.¹

A two-piece inflatable implant has no separate reservoir in the belly.¹ ²

Malleable (semi-rigid) implant
Two bendable rods keep the penis firm at all times. You bend it up for sex and down for daily life.¹ ² The penis is always firm. You can bend it down for daily wear, but it cannot be „deflated,“ so it can be harder to conceal.¹ ²

Before and after: what changes and what doesn’t
An implant makes the shaft of the penis rigid. It usually does not make the head of the penis (the glans) firmer.² Some men feel their erect penis is shorter than their natural erections were years ago. In one study cited by the American Urological Association (AUA), 72% of men said their length had decreased, yet measurements before surgery and six months after were statistically the same.² Ask your surgeon what to expect for your own body before surgery.
To see how an inflatable implant inflates and deflates, watch the animations on the inflatable penile implant page, and read our guide to penile implants. Product availability differs by country; see regulatory status.
Aus den Leitlinien
"The two currently available classes of penile implants include inflatable (two- and three-piece) and semi-rigid devices (malleable, mechanical and soft flexible)." (p. 55) [1]