"Pictured in the listing is a backbox with five green inserts on the top. There were no lamps or other special lights mounted inside to shine through these inserts. We asked designer John Borg if special lighting was intended and if any of these backboxes made it into production. He replied:

I believe I had some GI and flash in the backbox. It would cast a haze on the big molded topper. Costed out (was eliminated) before production. I had one of the early 30 or so prototypes and don’t remember if my game had these inserts added to the top of the backbox or not. I’m thinking not. [The game pictured] must have been an engineering sample they sold."

From http://www.ipdb.org/machine.cgi?id=2493 I also previously had one and it was nice to see them in the top, I like owning unique/oddities in pins.