system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] How did Ron recognize the invisibility cloak?

In the first Harry Potter book, when Harry first received the cloak, Ron almost immediately recognized it as an invisibility cloak. But later we learn that the cloak is the only one of it's kind. Granted, there are other, cruder invisibility cloaks with disillusionment charms woven into them etc. But it seems unlikely that they look exactly the same as Harry's cloak, which was one of the Deathly Hallows.
gpt
Invisibility cloaks aren’t one of a kind, they are rare.  What makes Harry’s special is that the invisibility charm doesn’t wear off.  Most only work like Harry’s for a brief time and then become more opaque. 

Dumbledore explains to Harry that the Peverell brothers made the deathly hallows and that they all are exceptional versions of semi common magical items.