In The Burning Crusade it is item level 115 and requires level 70. In Wrath of the Lich King it is item level 251 and requires level 80. In MoP Classic it is item level 115 and requires level 70.
Read from the World of Warcraft client build files (JournalEncounterItem, JournalEncounterCreature, Achievement) and the Blizzard Game Data quest API.
How Steelspine Faceguard Compares
Who It Suits
Mail is the armor type Evoker, Hunter and Shaman wear. With Agility or Intellect, Steelspine Faceguard suits Beast Mastery, Marksmanship and Survival Hunter; Elemental, Enhancement and Restoration Shaman; Devastation, Preservation and Augmentation Evoker.
Transmog Sets
Steelspine Faceguard is part of the transmog set Goldspine Plate (Warrior, Paladin and Death Knight only). The other 13 pieces:
Blizzard numbers items as they are created, so the named items next to ID 28671 (28666 to 28676) were usually added in the same batch as Steelspine Faceguard: the same quest line, zone, vendor or reward set.