Main materials:--The brake drum is made of brittle gray cast iron material. The brake drum 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 electromagnets:--After injection molding with PPS, the surface of the electromagnet is polished flat to ensure a close fit between the electromagnet and the brake drum surface during braking, achieving a better braking effectRegarding brake shoes:--The shear area and shear strength test of each finished brake shoe fully reflect our responsibility for customer safety.--The length of the brake pads for the same brake is different, and depending on the role of the leading and trailing shoes in the braking process, the lining of the trailing shoes is shorter than that of the leading shoesRegarding anti- corrosion performance:--The surface has a rust-resistant coating and good corrosion resistance.Self-adjustment:Automatically adjust the gap between the brake shoes and brake drums, and always maintain appropriate brake clearanceExcellent design:--High precision, no axial runout, use of high-speed bearings, high-temperature lithium grease; Complies with the G3000 standard in the USFit:--For 5,200lbs with Dexter, Al-Ko, Lippert, Quality and other brands trailer axles--Only works on models using L68149 inner cone and L44649 outer cone bearings trailer axlesKit Includes:--2x 6 on 5.5" brake drum--2x 25580 inner cone bearing--2x 15123 outer cone bearing--2x oil seal--2x dust cover-- 2x rubber plug dust cover--12x wheel hub nut--2x electromagnetic self- adjusting brake (left+right)--10x bolt--10x spring pad--10x nut--2x hexagonal slotted nut--2x flat washer--2x split pin