Key to Refurbished Shredder

Source
One key is gained upon completing the daily quest Shredder Repair.

You can use the key to get in a Refurbished Shredder in the forest around Venture Bay. The self-destruct hotkey can be used to one shot the elite captains in Venture Bay to complete Down With Captain Zorna! or Crush Captain Brightwater!.

Guides

 * http://www.youtube.com/watch?v=7aVWto_rhGQ