Main Materials: --The brake idler hub is made of brittle gray cast iron material. The brake idler hub is a cast iron piece, shaped like a bell-shaped drum, fixed to the tire and rotating at the same speed as the tire. Regarding Anti-corrosion Performance: --The surface has a rust-resistant coating Excellent Design: --High precision, no axial runout, use of high-speed bearings, high-temperature lithium grease; Complies with the G3000 standard in the US Fit: --Fit For 3,500lbs trailer axles; Only works on models for L44649 outer cone bearings and Replacemnet for L68149 inner cone bearings trailer axles Kit Includes: --1x 5 on 5" idler hub --1x inner cone bearing fit for L68149 --1x outer cone bearing fit for L44649 --1x grease seal --1x rubber plug dust cover --5x hub nut