This article originally appeared on VICE Indonesia.

When Indonesia’s police and National Narcotics Board conducted a sweep of a Bandung prison, they didn’t expect to confiscate dozens of makeshift tools used to insert penis implants. The practice of surgically inserting beads under the foreskin, known also as genital beading, is common among prisoners in the country.

Using tools crafted from lighters, toothbrushes, and other everyday objects, prisoners perform the simple procedure in-house on fellow inmates. The implants themselves are made of solid materials like wood, plastic from melted toothbrushes, or stone.

“The beads are inserted under the foreskin through a small incision, usually between three to six beads. It’s common in other prisons as well,” Gungun Gunawan, head of Jelekong Prison, told local media.

Recidivist Chandra Setiaji, who wrote a piece for VICE about genital beading last year, explained that prisoners undergo the procedure to make their penises appear more structured and to please their partners in the bedroom. He compared genital beading to ribbed condoms that supposedly increase stimulation for women.

These procedures are not risk-free. Since they are largely performed in prison, inmates risk infection and contracting blood-borne viruses. Those who have implants inserted are also prone to penile oedema and erectile dysfunction.

Catur, an inmate who goes by one name, makes a living performing penis implant surgeries in prison.

“The cost of living in prison is high, but I can take home Rp 150,000 to Rp 200,000 ($10.74 to $14.32) per procedure. For many men, the beads in their penis are like a souvenir from prison,” Catur told VICE.

The penis modification craze is not limited to Indonesia; a 2013 Sexual Health and Attitudes of Australian Prisoners Project (SHAAP)-funded study found that six percent of Australian prisoners have inserted some form of implant into their penis.

Sexologist Dr. Boyke Dian Nugraha said that while Indonesians go to extreme lengths to enlarge their penises, these methods are not actually effective.