Libra 10" x 2-1/4" Trailer Electric Brake Assembly one pair - 21003B Premium LIBRA brand OE 10" x 2-1/4" electric trailer brake assemblies (1 left + 1 right) for one axle works with most 3,500 lbs trailer axles in the market Center Hole Diameter: 3", 4 holes mounting, bolt circle diameter: 4", mounting bolts installed, no nuts included Exchange with Dexter brake # 023-026-00/023-027-00 Only sold by Libra Trailer Parts