Trailer Wheel Hub Assemblies connect the trailer tires to the trailer axle which facilitates their spin. The true purpose of the wheel hub is to serve as the glue between the tire and the axle. Be sure to accurately measure you necessary wheel hub based on your axle, as there are many size variations available for wheel hubs. We do offer our Trailer Hubs in kits, which will come with the necessary hardware to install your Trailer Hub (such as bearings, nuts, cotter pin, etc). If the wheel hub is incorrectly installed or is worn-out/corroded you will be more susceptible to the tires becoming un-aligned which could inevitably lead to more damages to your vehicle/trailer. You should always keep an eye on your hub assemblies, keep an eye out regularly for corrosion, cracking or other damages at least once a year (or once a quarter depending on how heavy your use is). If you have any questions regarding our products, please feel free to reach out to us with anything, we are more than happy to help out.