All unbraked trailer hubs come supplied with both outer and inner bearings placed beneath the dust cap. They also include the studs and nuts, which is a pivotal point when choosing the correct hubs. Choosing the correct hubs depends on the wheel size and stud pattern, as well as the boss size to fit the sub axle.
When fitting a hub to a suspension axle, ensure that the axle is perfectly clean and smear with a coat of hub grease, designed specifically for trailer application. A smear of grease should also be applied to the outer bearing shells and to the bearings themselves.
The hub of a trailer is a safety critical item. Take care when servicing and fitting the hubs that you avoid dirt and grit, and always use the correct grade of grease.