Our Heavy-Duty, Triple-Axle trailers, model PT28-3HD and model PT30-3HD, are built with 5" x 2", 11-Gauge Steel Tube Frames, additional Lateral Bracing, and come equipped with a standard 2-5/16" Coupler and standard Disc Brakes on two Axles. The PT32-3HD model, and PT34-3HD model are built with 5" x 2" x 3/16" enhanced wall-thickness Steel Tube Frames.