Chain of the Scarlet Crusade has 6 primary pieces, but also has several optional pieces. It is a mail set and requires level 30. The photo shows the six pieces plus tabard.
The Tabard isn’t required, as it looks like the chest piece except for the tails, but it does add to the set. There is also the Aegis of the Scarlet Commander for shield wearers. The boots and chestplate are BOE, so check the auction house for them. The remaining pieces drop in Scarlet Monastery.
For helm options: Raging Berserker’s Helm, Blood Knight Helm
For back options: Red Riding Hood’s Cloak, Battle Healer’s Cloak (Horde Only), Recovered Scarlet Onslaught Cape (Justice Points, Legacy), Gorn’s Discarded Cloak (Horde only)
For shoulder options: Herod’s Shoulder, Blood Knight Pauldrons