I bought one like this years ago and used it a few times over the years. Pulled it out a few days ago and it doesn't work anymore. I suspect the seals inside have glued themselves in place. I'll look at it some time in the next ten years if I get back to it. I would rather have this one than one made from a pump jack.

Installed some Bosch injector nozzles in an idi VW without a tester and they seem to be fine, big improvement. Nozzles made in India.