More progress on the male birth control front: First German inventor Clemens Bimek invented a valve that allows men to switch their sperm flow on and off at will. Then, scientists tested a birth control shot on a group of men, but the emotional side effects led researchers to believe that it is not safe enough to be used by the public. Now, a new male contraceptive gel has passed the (very scientific sounding) monkey test.

The new product is called Vasalgel. Once it’s injected into the tubes inside the penis that sperm swim down, it blocks their path. It’s the same concept as a vasectomy but far less extreme; if it works the way it’s supposed to, it should be far easier to reverse by simply introducing another injection that dissolves the gel.

The gel underwent a two-year trial and researchers determined that it’s both and effective—but only on primates. The next step is testing the gel on actual male humans. Only after then will the product be available on the market, and it’ll take at least a few years. However, one contraceptive gel called RISUG is already being tested on men in India. Similar to the IUD for women, contraceptive gel is supposed to be long-term birth control solution for men.

The gel was tested on 16 primates at the University of California. The monkeys were given the injection and then released into a population of fertile females. Though many of the primates mated, none of the females became pregnant.

Unlike the hormone shot, the gel had no negative side effects on the primate test subjects, and only in one case was surgery necessary because of a damaged tube.

Although the gel is effective in preventing pregnancy, the challenge now is to figure out if it can be reversed. Researchers have only been able to effectively reverse the gel injection in rabbits, whose genetics are a far cry from the human genome. That means more studies, more research, and—just like we are used to hearing—more waiting until we know when male birth control (besides the condom) can be safely used by men.

Dr. Anatole Menon-Johanssonm, who works for the sexual health charity Brook, told the BBC that this method, which he terms a “reversible vasectomy,” might be more appealing to men than asking them to take hormones, which women have already been doing for decades now, especially now that they know how uncomfortable the side effects can be.

As I’ve said before, don’t get your hopes up: This is still a small breakthrough in an area that science has been struggling to understand for years; this one in particular won’t see any human tests for another three years.