Here it is. They're a special type of magnifying glasses used by jewelers, scientists, and archaeologists.
7 seconds sound clip from Scooby-Doo, Where Are You! - What a Night for a Knight (S1E1).
You can hear this line at 00:05:57.708 in the Blu-ray version of the episode.
Quote context
[...]
- Well, it's got me, like, hungry. When do we eat?
- They look like some crazy kind of glasses.
- He must have found them at the museum.
- Man, I wonder what kind of groovy things you see with those.
- Well, there's one way to find out.
- And hold on to your hula-hoops... It says here made only in England.
- England?
- That settles it. There's something fishy going on in that museum.
- Museum?
- Right, Scoob, tonight we're going fishing.
- This place is locked up tighter than a drum.
[...]