Read from the World of Warcraft client build files (JournalEncounterItem, JournalEncounterCreature, Achievement) and the Blizzard Game Data quest API.
How Gatekeeper's Girdle Compares
Who It Suits
Mail is the armor type Evoker, Hunter and Shaman wear. With Agility or Intellect, Gatekeeper's Girdle suits Beast Mastery, Marksmanship and Survival Hunter; Elemental, Enhancement and Restoration Shaman; Devastation, Preservation and Augmentation Evoker.
Transmog Sets
Gatekeeper's Girdle is part of the transmog set Centaur Dungeon Harness (Hunter, Shaman and Evoker only). The other 16 pieces:
Blizzard numbers items as they are created, so the named items next to ID 193794 (193789 to 193799) were usually added in the same batch as Gatekeeper's Girdle: the same quest line, zone, vendor or reward set.