The fully assembled pre-lubed Ultra-Pack unit features a greasing system that lets you repack bearings without removing the hub so blowing out the rear seal is no longer a concern. This new proprietary system allows you to quickly and easily insert fresh grease through the zerk fitting. Grease flows through both the inner and outer bearing, pushing old grease out the front for a complete repack. Disassembly is not required. Simply hook grease gun to the zerk fitting to purge contaminated grease. Upgraded triple-lip, spring-loaded seal protects bearings from corrosion. High-speed electro-plated construction resists rust. Includes hub with bearings, seal, grease cap with zerk, stud nuts and dust cap installation tool. Works with your existing spindle.