Operate efficiently at high and low pressures.Hand-operatedPressure adjustable from 1, 000 to 10, 000 psi by operator with just a screwdriver and gauge.Polished steel control rotor and bronze spools for long life and consistent operation.Models for use with both single-acting and double-acting cylinders.Field interchangeable on HP-520 (manual) andHP-560 (electric) series pumps.