New 7" X 1-1/4" Trailer Electric Brake Assembly (1 Right + 1 Left) - 21001 New 7" x 1-1/4" electric trailer brake assemblies (1 left + 1 right) for one axle works with most 2,000 - 2,500 lbs trailer axles in the market Center Hole Diameter: 3", 4 bolts mounting, bolt circle diameter: 4", mounting bolts installed, no nuts included