The King BMW N55B30A/N53B30A/N52B30A (Size STD) Main Bearing Set is a high-performance set of main bearings for BMW engines. It is designed to provide superior durability and performance for high-performance engines. The set includes four main bearings, made from high-quality materials and precision-machined for a perfect fit. The bearings are designed to reduce friction, improve engine performance, and increase engine life. The set is also designed to provide optimum oil flow and lubrication, helping to reduce engine wear and tear. This set is a great choice for those looking to upgrade their BMW engine.