King MB5013XP XP Series Main Bearings for GM Gen III IV LS & Gen V LT EnginesKings XP series incorporates a strengthened tri metal structure called pMax Black. This unique metal composition was developed to meet the ongoing demand for increased engine bearing load capacity. 24% greater load capacity 17% more fatigue resistance SecureBond A micro etch process that improves multi layer adhesion and structural integrity Compatible with all crankshafts Intermediate layer: Copper based alloy strengthened by 4. 5% tin Industrys