This is a functioning packard shutter with the sync connections. I hooked my hose & bulb (not included) to it and it still fires fine. I don't have any way to check the sync but they are pretty simple. I used one similar to this to fire my strobes a couple of years ago.
Outside dimensions are 4.75" x 4.75" and the hole diameter is 2 1/2".
No idea what these go for lately, so I'll say $50 shipped in the USA, USPS money order preferred. If that price is crazy, make me an offer.