Here’s a short original English description specifically for the UN-type hydraulic seal (note: “UN” typically refers to the asymmetric U-ring with a stepped/notched lip design, commonly used in heavy-duty cylinders):
Asymmetric U-ring with stepped sealing lip. Pressure-activated lip geometry ensures zero-leakage performance at low and high pressures. Optimized micro-finish contact reduces stick-slip and wear. Superior extrusion resistance with compact cross-section. Suited for high-cycle, high-pressure rod applications. Material: abrasion-resistant polyurethane. Temp: –35°C to +100°C. Pressure: up to 35 MPa.
Original source: Hydraulic seal https://www.bszzseal.com/
