Red-red decoder spectacle often used for commercial purposes.
The purpose is to read green printed text that is printed behind red printed text.
This requires a very accurate chosen colour for printing.
Often a chaotic patern is used to print over the to be discovered text or image.
Then you prevent to discover the picture without spectacle.
The opposite spectacle is green-reen.
These spectacles are intend to be used once or twice.
For that reason they cannot be returned.
Minimum order quantity is 4 pieces.