These hydraulic rod seals are of an unloaded U-cup, double-lip design with a secondary dynamic sealing lip. They are made of an ether-based thermoplastic polyurethane, provide good resistance to hydrolysis (attack from moisture) and have good low temperature resistance. They are compact, especially suitable where small radial seal sections are required, i.e. 4 to 6 mm (0.039 to 0.236 in), and retain a good sealing performance at low- or zero-pressure conditions.