Read from the World of Warcraft client build files.
How Ered'ruin Helm Compares
Who It Suits
Mail is the armor type Evoker, Hunter and Shaman wear. With Agility or Intellect, Ered'ruin Helm suits Beast Mastery, Marksmanship and Survival Hunter; Elemental, Enhancement and Restoration Shaman; Devastation, Preservation and Augmentation Evoker.
Similar Items
The 10 items nearest to Ered'ruin Helm (item level 13) in item level among Armor > Mail, Head slot, from item level 19 to 20.
Blizzard numbers items as they are created, so the named items next to ID 240554 (240549 to 240559) were usually added in the same batch as Ered'ruin Helm: the same quest line, zone, vendor or reward set.