Read from the World of Warcraft client build files.
How Galactic Gladiator's Silk Cap Compares
Who It Suits
Cloth is the armor type Mage, Priest and Warlock wear. With Intellect, Galactic Gladiator's Silk Cap suits Discipline, Holy and Shadow Priest; Arcane, Fire and Frost Mage; Affliction, Demonology and Destruction Warlock.
Transmog Sets
Galactic Gladiator's Silk Cap is part of the transmog set Galactic Gladiator's Silk Armor (Mage only), which the Appearances collection lists in 3 versions. The other 16 pieces:
Items Numbered Next to Galactic Gladiator's Silk Cap
Blizzard numbers items as they are created, so the named items next to ID 255364 (255359 to 255369) were usually added in the same batch as Galactic Gladiator's Silk Cap: the same quest line, zone, vendor or reward set.