Update 01/16/2016: PCB available via website at http://www.pinitech.com/products/gottlieb_universaltester.php
This is a diagnostic tool / board for use at the bench, when diagnosing Gottlieb Sys80 MPU board issues.. born from Leon's creation here: http://www.pinwiki.com/wiki/index.php?title=Leon_Borre_Gottlieb_System_80_CPU_Board_Repair
The heart of things are the test ROMs, but this board makes it easier to plug-and-play with diagnosing rather than having to connect jumpers or make any modifications to the board. It's a basic board that plugs into the TC1 socket on the top of the Sys80 MPU board and has an LED connected to address A6 (this is the address signal that Leon used for blinking the LED as described in the link above).
It's now recommended that you utilize this board with Marco's Sys80 Test ROM instead of Leon's, as Marco's ROMs are much more extensive in what they test & he's also active here on the forums.