This 4-pack of 12.25" x 3.375" hydraulic trailer brake assemblies is designed for trailers with 9,000–10,000 lb general duty axles, providing a complete replacement solution for both axles on tandem setups. The kit includes two left-hand and two right-hand brake assemblies, each fully pre-assembled with brake shoes, return springs, wheel cylinders, and adjusters. These brakes use a forward self-adjusting system, which helps maintain consistent shoe-to-drum clearance without manual adjustment—improving brake responsiveness and lifespan. Each unit mounts easily to a 7-bolt flange and is built from heavy-duty materials engineered to handle the rigors of frequent hauling under heavy loads. This kit directly replaces OEM parts Dexter K23-410-00 and K23-411-00, making it a trusted upgrade for livestock trailers, flatbeds, equipment haulers, and dump trailers. Whether you're doing preventive maintenance or a full brake overhaul, this 4-piece set ensures you're covered with performance you can trust.