Essentially -- it's a gel that's injected into the vas def which doesn't actually block the flow totally (which sometimes causes side effects like granuloma in vasectomy), but rather it disrupts sperm cell membranes, but allowing the remains to pass through.

It is reversed simply by flushing it out with saline.

Last time I donated to the project it was at the live rabbit trials stage with Parsemuns Foundation?

(OH WAIT IT HAS BEEN USED IN HUMANS IN THE USA (see wired link below)

RISUG was used in humans for like 20 years with good results I believe.

Really don't understand why this one hasn't gained traction.

https://www.planaformen.com/vasalgel

https://en.wikipedia.org/wiki/Reversible_inhibition_of_sperm_under_guidance

https://www.wired.com/story/male-contraceptive-contraline-vasalgel-hydrogel/

(Ohh right the rabbit study was for reversibility)

https://pmc.ncbi.nlm.nih.gov/articles/PMC5381074/