The procedure is known by the clunky acronym RISUG (for reversible inhibition of sperm under guidance), but it is in fact quite elegant: The substance that Das injected was a nontoxic polymer that forms a coating on the inside of the vas. As sperm flow past, they are chemically incapacitated, rendering them unable to fertilize an egg.

Wow, this is pretty awesome. Could be a game changer for guys.