ARP 230-4201 Cylinder Head Studs Kit for 2001-current Chevrolet Duramax Diesel 6.6L LB7 LLY LBZ LMN EnginesARP's Pro Series Head Studs are made with heat treated and thread rolled 8740 material with an incredible 200,000 PSI tensile strength rating for better load distribution. They also come with ARP's unique 12 point nuts and hardened parallel washers, giving you the improved torque reading. Fastener Style: Stud Head Style: 12 point Fastener Finish: Black oxide Washers Included: Yes Quantity: Sold as a kit. Notes: Fits LB7, LLY, LBZ, LMM engines.