New 10" x 2-1/4" Trailer Hydraulic Free Backing Marine Brake Assembly Pair Set - 21016 New OE 10" x 2-1/4" Hydraulic free backing marine trailer brake assemblies (1 left + 1 right) for one axle works with most 3,500 lbs trailer axles in the market Advanced DACROMET coating for maximum corrosion resistance Stainless steel or aluminum hardware or parts Center Hole Diameter: 3",4 holes mounting, bolt circle diameter: 4", mounting bolts not included