A penile prosthesis is another treatment option for men with erectile dysfunction (ED). These devices are either malleable or inflatable. The simplest type of prosthesis consists of a pair of malleable (bendable) rods surgically implanted within the erection chambers of the penis. With this type of implant the penis is always semi-rigid and merely needs to be lifted or adjusted into the erect position to initiate sex. Today, many men choose a hydraulic, inflatable prosthesis, which allows a man to have an erection whenever he chooses and is much easier to conceal. It is also more natural.