Grievous Gladiator's Mooncloth Helm is part of the transmog set Grievous Gladiator's Satin Armor (Priest only), which the Appearances collection lists in 2 versions. The other 13 pieces:
Built from the World of Warcraft client build files and recorded Auction House snapshots.
Where Grievous Gladiator's Mooncloth Helm Fits
Other Items Named Grievous Gladiator's Mooncloth Helm
4 other items in the current build are also called Grievous Gladiator's Mooncloth Helm. Same-name entries are usually a different rank, faction, quest stage or reward track of the same object.
Items Numbered Next to Grievous Gladiator's Mooncloth Helm
Blizzard numbers items as they are created, so the named items next to ID 100408 (100403 to 100413) were usually added in the same batch as Grievous Gladiator's Mooncloth Helm: the same quest line, zone, vendor or reward set.