Am I even in the ballpark? Probably not <.< Please explain what these do
It is an AC power switch, which is controlled by a lower voltage and current (like a relay). It is solid-state because the switching is not done by a mechanical switch and solenoid, but by semiconductor components (thyristors). This is an easy way of hooking up computer control for automation and industrial control, these days you would do things like reset your mining computer with them remotely with an arduino or parallel port (the original thread for which I posted them for sale). The ones with date codes look to be 1984, and they have a standard size and input across manufacturers, probably because governments require multiple sources for components.
http://www.youtube.com/watch?v=kUE4QyIyb4Y
