Bearings incorporate larger balls providing larger load carrying capacity, and now sit on the axle instead of the wheel collars Upgrade kit includes bearings, seals, watertight wheel collars, bearing spacer and two sets of O-rings Collars and bearing spacer made of military hard anodizing to prevent wear Collars incorporate Pivot Works watertight O-ring design to keep hubs dry Replacement bearings and seals sold separately. BEARING WHL RR T12-000