Are You Color Blind? Inexpensive Solution.

And just what am I supposed to do with them?

Well, I will use them to check out lights on computer peripherals. The ones which change
from red to green, for example, after a recharge.
When I find my Two Cent Piece which is covered in verdigris I will check out the green areas.

If it were not for the label I would not be able to tell them apart.
The "Johann Sebastian" is white letters on either red or green.
Notice how one filter let's part pass through and the other filter not.
The green effectively changes red to black and vice versa.

I'll try to send larger pics to anyone who allows private messages.