BOLT Receiver Lock 

Security is important to you, but your time is priceless. Why risk a LOCKOUT due to a lost key? Lock it down with BOLT, Breakthrough One-Key Lock Technology! The BOLT Receiver Lock is the one key solution to all of your towing needs. Some of the features of the BOLT Receiver Lock include:
-Auto Return Spring Locks Automatically When Key Is Removed
-Double Ball Bearing Locking Mechanism
-Plate Tumbler Sidebar To Prevent Picking and Bumping
-Stainless Steel Lock Shutter To Keep Out Dirt And Moisture
-Opens With Your Vehicle Ignition Key
-Weatherproof
-Limited Lifetime Warranty