Trailer Tailgate Hinge Hinge for the Explorer Box or any Home-Built Camping Trailer. 3 1/2" gate style hinge. Black or Zinc Sold individually. Upgrade your trailer's functionality with our durable Trailer Tailgate Hinge. Made for the Explorer Box or any Home-Built Camping Trailer, our 3 1/2" gate style hinge is available in black or zinc and sold individually. Trust in our high-quality materials and precision engineering for smooth and reliable use every time.