• Belt of Slithering Serpents
• Heroic
• Item Level 353Disenchants into:
  [Abyss Crystal]: 1-2
• Binds when picked up
  
• Leather
• Waist
• 913 Armor
• +220 Agility
  +360 Stamina
• Blue Socket
• Socket Bonus: +10 Expertise Rating
• Durability 55 / 55
• Requires Level 85
• Equip: Increases your haste rating by 142 (1.11% @ L85).
  Equip: Increases your mastery rating by 155 (0.86% @ L85).
• 
• Sell Price: 8 45 9

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