Superior materials lead to superior performance. When you replace and upgrade your failing OE ball joints with a heavy-duty Yukon unit you get a ball joint built to the highest standards of quality and durability. Its housing is CNC-machined from forged SAE 1045 carbon alloy steel and the ball stud is made from induction heat-treated, hot-forged 4140 chromoly. The upper joints bearing features a carbon steel design that is superior to the OE joint. The lower joint uses military-grade acetal bearings because of their advanced anti-friction properties and dimensional stability. Ball joints are only as durable as the protection provided by their rubber boots. These Yukon ball joints feature a two-staged approach with a synthetic Neoprene/CR outer boot and an inner seal/pancake boot that safeguard the spherical joint and bucket against gritty road grime, oil, gas, and engine fluids, and extreme temperatures. This kit replaces the upper and lower front ball joints on both sides and includes Grade 8 hardware, castle nuts, c-clips, cotter pins, and zerk fittings.