When it comes to contraceptives, men really only have one of two options: condoms or a vasectomy. Most people feel that condoms detract from the experience of sex, and a vasectomy is a potentially permanent surgical procedure, so for people who want the full enjoyment of sex without the risk of becoming infertile, oral contraceptives for women are pretty much the only option. At least, that’s the way things used be before a German carpenter by the name of Clemens Bimek created a device that allows men to literally switch their fertility off and on whenever they want. It achieves the same results as a vasectomy, but without any of the risks involved.

Imagine if there were a type of birth control that could be activated by a button. A German carpenter invented a device that sounds like it came straight from science fiction—male contraception that allows a man to turn his sperm flow off and on with just a flick of a switch. Clemens Bimek first came up with the idea of a spermatic duct valve around 20 years ago while watching a documentary about contraception. According to German magazine Spiegel (via The Telegraph), Bimek filed a patent in 2000, then built the first prototype of the Bimek SLV in 2006. “Many of the doctors I consulted didn’t take me seriously. But there were some who encouraged me to go on tinkering and helped me with their expertise,” he said. During a half-hour operation, tiny valves are implanted in the vas deferens and controlled by a switch that is easily accessed by hand through the scrotum skin. The Bimek SLV website describes the switch as being “as small as a gummy bear.” When the valve is closed, sperm cells are prevented from being released during ejaculation, leaving the seminal fluid sterile. The result is similar to a vasectomy, except the patient can allow the sperm to flow at any time whereas vasectomies sometimes cannot be reversed.