Thief Armor is part of the Hexxit Gear mod. It is one of three sets of Hexxit Gear Armor. When all four parts of the armor are equipped, the player will experience special abilities, as well as giving the player the maximum 20 Armor Points, the equivalent of a full set of diamond armour.
Once all four pieces of armor are equipped, the player acquires unlimited Night Vision and Strength potion effects. You also gain an significant speed boost. The speed boost will work even on a chocobo so it is recommended to take off a piece of the armor before riding a chocobo (the world may not load fast enough to go that speed and may also cause lag). There is a bug with this armor involving Dimensional Doors. If you enter a Dimensional Door with the night vision buff, everything will appear completely black until the buff expires. Only particle effects, such as torch flames or notes from note blocks, will be visible. The Tribal Armor also shares this bug.
For the full set you will need:
Thiefs Hood (3 Armor Points)
Thiefs Chestpiece (8 Armor Points)
Thiefs Leggings (6 Armor Points)
Thiefs Boots (3 Armor Points)