The ARP 135-5201 Big Block Chevy 4 Bolt Block 8740 Chrome Moly Main Bolt Kit is a high-performance auto part designed for racing and performance vehicles. Manufactured by ARP in the United States, this kit includes durable chrome moly main bolts to enhance the strength and reliability of the engine block. The 4 bolt design provides increased clamping force for improved sealing and reduced blow-by. With a reputation for quality and performance, this kit is a popular choice among car enthusiasts looking to upgrade their engine components for improved performance on the track or drag strip.