Simply a glare screen, because it clearly states what it protects one against, I guess.
Answer:
Speakers.
Explanation: Cause they only output sound, and are devices, further more they are not used to output images, like how could speakers output images using sound? They can't.
Definition
URL a.k.a uniform resource locater, is simply the address of a World Wide Webpage.
Sentence example:
"Type a URL into a browser's address bar."
