Rusty, I BOUGHT ANOTHER FLUKE!!!!

The last unit is a power supply that is adjustable from .001 dc volts up to 24 volts, 001 of a volt at a time if you want too.

The plugins on the one 555 are also dual beam. You can have 4 beams going at once.
The unit missing the 2 plugins has time delays that the other unit does not.
Some where I have the manuals to them.