Bulldog 580412 Universal Stainless Steel 5/8" Trailer Dogbone Lock (for 2-1/2" Sq. Class V Receivers) Bulldog lifelong locks feature stronger break resistance, a dual self-locking design, and a high security square key design Class V Stainless Steel lock components are strong yet attractive - strength doesn't have to be ugly Ball bearing Locking mechanism; dust cap protects lock mechanism from the elements 5/8 inch dogbone lock fits class V 2-1/2 inch square receivers Backed by Bulldog 1 year limited warranty