Radial Oil Seals TRF are reinforced metal cased radial lip seals with dust lip. The supplementary metal inner ring provides superior stiffness. This type is recommended for use in heavily polluted environments. To achieve a long lifetime, a suitable lubricant between the two sealing lips should be applied. As the static sealing between housing and metallic shell is limited, low viscosity media can "creep". Better performance can be achieved with an epoxy based resin outer diameter coating.