• Leggings of Swift Reflexes
• Item Level 219Disenchants into:
  [Abyss Crystal]: 1-2
• Binds when picked up
  
• Leather
• Legs
• 511 Armor
• +106 Agility
  +92 Stamina
• Durability 90 / 90
• Requires Level 80
• Equip: Improves critical strike rating by 53.
  Equip: Improves haste rating by 76.
  Equip: Increases attack power by 162.
• 
• Sell Price: 10 80 77

Source

This item drops from Assembly of Iron in the 10-man version of Ulduar.

Patch changes

• Patch 3.1.0 (14-Apr-2009): Added. 
  

External links

• Battle.net (EU)
• Wowhead
• Thottbot
• WoWDB