With the flip of two switches, men could one day curb their sperm flow and activate easily reversible birth control, according to ballsy German inventor Clemens Bimek.

Bimek, a carpenter who was frustrated with the lack of male-controlled contraceptives, came up with the idea after watching a television show about anatomy. Determined that his sperm shut-off method would work, the spunky creator patented the idea in 2000 and tested it out on himself (in collaboration with a surgeon) in 2009—and so far so good, he reports. Bimek intends to organize a 25-person clinical trial this year of the method, called the Bimek SLV.

The Bimek valve.

The Bimek SLV works by implanting two devices—shut-off valves—in the scrotum. The valves are each about the size of a gummy bear and made of non-magnetic metallic components and a biocompatible polymer already used in medical implants. The devices get attached to the vas deferentia, the two ducts that transfer sperm from the testicles to the urethra. During implantation, each vas deferens is cut and the ends are plugged into the in and out tubes of a valve.