Vintage PYREX 662-668 C Replacement Lid, Square (rare find)

Description

Vintage lid measures 6" x 6" at its outermost edges but is 5" x 5" at the inner lip.
It has approximately 8 small nicks on the inner lip (underside).
There are 2 nicks that are right next to each other on the outer edge. Together they are 3/8" in length.
The glass has some cloudy and/or discoloration that can only be seen if you examine it closely.
The lettering on one side says "662-668 C MADE IN USA"
The lettering on the other side says"PYREX T.M. REG. U.S. PAT. OFF."