This seal is mainly used with high pressure and the backup ring o!sets large gaps without extrusion. The asymmetric lips are designed to differentiate the behaviour of the lips on the static and dynamic surfaces: the static lip is flexible and more sensitive to pressure fluctuations; the dynamic lip is shorter and stronger to concentrate load against the dynamic surface. Wear and dry run are largely prevented by additional lubricant retained within the gap created by the secondary lip. In some cases this second sealing lip may even act as a substitute for a costly tandem sealing system when complete sealing under certain working conditions can only be achieved by two seals placed one behind the other in separate housing. The material used to produce this seal is a polyurethane compound that ensures excellent properties on wear-resistance, extended service life and resistance against extrusion.