Primal Gladiator's Mail Leggings is part of the transmog set Primal Gladiator's Ringmail Armor (Shaman only), which the Appearances collection lists in 2 versions. The other 16 pieces:
Items Numbered Next to Primal Gladiator's Mail Leggings
Blizzard numbers items as they are created, so the named items next to ID 115945 (115940 to 115950) were usually added in the same batch as Primal Gladiator's Mail Leggings: the same quest line, zone, vendor or reward set.