Read from the World of Warcraft client build files (JournalEncounterItem, JournalEncounterCreature, Achievement) and the Blizzard Game Data quest API.
How Plague-Resistant Headcover Compares
Who It Suits
Leather is the armor type Demon Hunter, Druid, Monk and Rogue wear. With Agility or Intellect, Plague-Resistant Headcover suits Assassination, Outlaw and Subtlety Rogue; Brewmaster, Mistweaver and Windwalker Monk; Balance, Feral, Guardian and Restoration Druid; Havoc, Vengeance and Devourer Demon Hunter.
Transmog Sets
Plague-Resistant Headcover is part of the transmog set Stormheart Raiment (Druid only). The other 16 pieces:
Blizzard numbers items as they are created, so the named items next to ID 147740 (147735 to 147745) were usually added in the same batch as Plague-Resistant Headcover: the same quest line, zone, vendor or reward set.