Not sure when this item was manufacturered.  It was put out by Jay Leslie, who owns rights to many of Ed Mellon's effects.  But Spectra mental is no longer offered by Leslie.  I am guessing it was sold in the mid-1990's, but might be earlier.  (Instruction sheet is typeset with a typewriter...)

The effect is a quick and effective prediction of which color a spectator will freely choose from three colored cards.  It looks like this:  Magician shows an envelope, and removes three  cardboard cards from within.  (The cards are about the size of bridge-size playing cards.)    The three cards are blue, red and green.  The magi turns away for a moment and puts one card in the envelope, and the other two in his pocket.  Turning back to the spectator, the magi puts the envelope on the table.  The spectator names ANY color of the three.  (No force.  let's say she names Green).   The magi immediately takes the blue and red cards from his pocket and turns the envelope over.  The green card can be seen through a hole cut in the envelope.  "I knew you would say green.  Everybody says green!"

Of course, this works no matter which color they name.  Mellon has engineered three outs within the same prediction envelope in a way that is so clever, it will make you smile when you perform this.  Like most Ed Mellon mentalism, the method is diabolical and simple at the same time!

This set of Spectra-Mental props are in very good shape -- the red card has a slight crease in it.  (Look at the picture).  This does not interfere with the effect.  Other cards and envelope are in excellent condition.  Complete with original packaging envelope and instruction sheet.