Primal Gladiator's Copperskin Boots is part of the transmog set Primal Gladiator's Ironskin Armor (Monk only), which the Appearances collection lists in 2 versions. The other 13 pieces:
Items Numbered Next to Primal Gladiator's Copperskin Boots
Blizzard numbers items as they are created, so the named items next to ID 115966 (115961 to 115971) were usually added in the same batch as Primal Gladiator's Copperskin Boots: the same quest line, zone, vendor or reward set.