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 : 1410-44539 WE61274 91-44539 94-44539 S511030 NT511030 WH511030 H511030 511030 GRW39 TRB-511030, Kit Includes: 2x Rear Wheel Bearing (Both Side), Part Reference Numbers : 1410-44539 WE61274 91-44539 94-44539 S511030 NT511030 WH511030 H511030 511030 GRW39 TRB-511030