... . In addition, all seals are manufactured to US specification, and being 100% hydro-pressure tested before delivery. Rod surface treatment ... CS nitrile expanderB. Piston OD seal(A type piston) Polyurethane U-capC. Tube seal O-ring(1)+back up ring ... . Products covering hydraulic cylinders, pistons, flanges, valves parts, casting and forging parts, engineering goods, etc.5. Quality control following 3 ...