PU U Seal is designed in the shape of the letter U and is made from polyurethane (PU) material. It is a type of rod seal that is used in hydraulic cylinders to prevent hydraulic fluid from leaking out of the cylinder along the rod. The PU U seal is designed to fit tightly around the rod and make a seal against the cylinder wall. PU is a popular material for hydraulic seals because it has good abrasion resistance, excellent resilience, and a high load-bearing capacity.