This genuine spare part kit is designed to restore the seal integrity of your HMV series hydraulic nut. It contains two precision O-rings essential for piston sealing: Inner Piston Seal: Ensures pressure containment within the piston bore. Outer Piston Seal: Maintains a leak-proof barrier on the piston’s exterior surface. Compatibility: Specifically engineered for hydraulic nut size 150, including models HMV 150E and HMVC 150E.