Featuring a hot-forged sockets professional quality, made of high-grade CHROME MOLYBDENUM ALLOY STEEL, for guaranteeing long life, safety, and durability of sockets. ■ Heat treated for the best combination of strength and impact resistance. ■ Optimum wall thickness design for strength and access on fasteners having restrictions. All dimension precision to meet industrial specifications. ■ Black phosphate coated to rustproof.