Window screen - what is the black murky type of peak I see on some houses? To run down grill?

Help! almost fridge and freezers?
Answers:    Mine is a pet screening, made so that my nutso cats won't claw holes in the screening close to they did with the other stuff. Now if they with the sole purpose would quit pulling at the corners so that they pull the spline loose!
Need give support to selling elder home?
It's bronze fiberglass blind. Also known as black to folks not in the peak bussiness.
What is the difference surrounded by a 4...