This is an optical slave that plugs into any strobe with a Female Household receptor. It "sees" the light from any other line of sight flash unit within 30', and fires its connected strobe instantaneously.
If for some reason it doesn't fire, just "reverse the polarity" by plugging it in the opposite way.
Bought this to sync my Novatron 500 VR with other wireless strobes. It would not trigger the Novatron even when the other strobe was pointed directly at it from 2 ft away. I had to revert to a wired solution to trigger the Novatron. Either I received a defective unit or it does not work with Novatron power packs.
I was in the middle of a shoot with a model and using my speedotron set-up, when all of a sudden after a mere 20 years, my slave died on me. I panicked that I wouldn't be able to replace something that must be so antiquated...but nay, B and H had just what I needed in stock and I received it within days. It works perfectly and it's so simple. Just plug it into your power pack and go!