Penile implants are urological surgical procedures, primarily for the treatment of erectile dysfunction and Peyronie's disease (scar tissue buildup within the penis) as opposed to enlargement as is commonly believed. Although there are many distinct types of implants, most fall into one of two categories: malleable and inflatable. Penile implants are urological surgical procedures, primarily for the treatment of erectile dysfunction and Peyronie's disease (scar tissue buildup within the penis) as opposed to enlargement as is commonly believed. Although there are many distinct types of implants, most fall into one of two categories: malleable and inflatable. The malleable penile prosthesis is a set of rods implanted into the corpora of the penis. The rods are hard, but are 'malleable' in the sense that they can be adjusted manually into the erect position. The inflatable penile implant, more recently developed, uses a pump system. Saline from a small reservoir, implanted in the lower abdomen, is moved by manual pressure on a small pump, located, with the relief valve, in the scrotum. The saline is then pumped into bilateral chambers implanted in the shaft of the penis, which replace the non- or minimally-functioning erectile tissue. This produces an erection. The glans of the penis, however, remains unaffected. Ninety to ninety five percent of inflatable prostheses produce erections suitable for sexual intercourse. In the United States, the inflateable prothesis has largely replaced the malleable one. A practice dating back to 16th century, and originating in Southeast Asia, it was not document to occur between the mid-17th century until the late 20th Century. The penis would receive a small incision, and tiny balls are placed underneath the skin. The purpose of the implant is alleged to increase the pleasure of a sexual partner. In 1999, a study found that the procedure had occurred to 57% of randomly selected Filipino seaman. In the late 20th Century, and early 21st century these balls were made of plastic. Other potential material which the balls maybe made of include metal, glass, or minerals. The practice also occurs outside of the Filipino mariner community, with implant recipient also documented in Japan and Cuba.