These are new old stock acrylic watch crystals with a cyclops window. They are in there original, little labeled envelopes. They came three in a glassine envelope. 

Lot has TWO of the glassine envelopes, with 3 crystals in each.

So you will be getting SIX crystals. They are new in original packaging. They have been lying in my father's watch effects since the 1970’s. He was a watchmaker between1960 and his death in 1996.

They are made in Hong Kong. The company was Electra-Edge.  My father labeled them as “calendar, Rolex style" 

As you can see by the envelope they are 31 millimeter in diameter.  The 10.5  millimeter I believe is the measurement from center of crystal to center of  cyclops. 

Have more of these, and lots of vintage acrylic crystals.