Core made of High-Carbon AISI 52100 Chromium Alloy Steel features higher wear resistance, fatigue strength and steel hardness, Premium quality MolyPro™ NLGI Grade 2 Molybdenum Grease (MoS2) to minimize wear and reduce friction providing longer lasting performance, Exclusive multi-lip seals are made with ProSeal™ Nitrile Rubber (NBR) which can successfully function at high delta of temperatures while retaining its flexibility and sealing performance, Inner rings are made of Case-Hardened Steel for improved resistance to surface wear and contact fatigue, Thickness and metallurgy electronically validated for manufacturing consistency, SAE J1714, J2525 and J2535 validated for OEM load-carrying capacity, durability, and performance characteristics, Part Reference Numbers : 1410-49518 WE61212 91-49518 94-49518 S513150 NT513150 WH513150 513150 FW132, Part Reference Numbers : 1410-44431 WE60919 91-44431 94-44431 S511028 NT511028 WH511028 H511028 511028 GRW258 TRB-511028, Kit Includes: 2x Front Wheel Bearing (Both Side) + 2x Rear Wheel Bearing (Both Side)