• Serpentine Leggings
• Heroic
• Item Level 353Disenchants into:
  [Abyss Crystal]: 1-2
• Binds when picked up
  
• Cloth
• Legs
• 1057 Armor
• +484 Stamina
  +283 Intellect
• Red Socket
  Blue Socket
• Socket Bonus: +20 Haste Rating
• Durability 120 / 120
• Requires Level 85
• Equip: Increases your hit rating by 211 (1.76% @ L85).
  Equip: Increases your haste rating by 176 (1.37% @ L85).
• 
• Sell Price: 13 57 14

Source

This item drops from High Priest Venoxis in the heroic-only 5-player Zul'Gurub (instance) for players at level 85.

Patch changes

• Patch 4.1.0 (26-Apr-2011): Added. 
  

External links

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