Harken’s integral hydraulic backstay adjuster provides the power to optimize sail shape quickly. The cylinder features a built-in, double-acting pump that delivers oil when the handle is both pushed and pulled. This moves oil through the system twice as fast as single-acting pumps on other integrals. Assemblies include a hardcoat-anodized aluminum cylinder and pump, valve, and stainless pump handle with three attachment options: pin installs handle permanently; O-ring secures handle in socket, but is not permanent; nonlocking handle installs without O-ring and roll pin. All pins and plugs are stainless steel. Cylinders include a clevis on both ends. Standard eye-jaw toggles fit all Harken cylinders. The pressure-release knob turns clockwise to close and pump, counterclockwise to release. When closing the pump, the knob cannot be over-tightened by hand, preventing damage to the valve. Release speed depends on how far open the knob is turned. Pressure relief is factory set to prevent crew from over-tensioning the backstay. Harken integral backstay adjusters come in four sizes to fit boats with 5 - 10 mm (7/32 - 3/8") wire—approximately 9 - 18 m (30 - 60').