This listing is for 4 U-Bolts and 4 Backing Plates. High quality OEM grade U-bolts / N-bolts suitable for use on trailers, frames etc... 6mm (1/4") Thick Backing Plates. High Tensile suitable for higher load and more critical areas. Not to be confused with cheaper bolts. M10 Thread (10mm diameter). Sizes; 80mm internal width, 75mm total internal length, 30mm long threaded section. Zinc & Gold Plated.