Harkens 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, gauge, 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.

An analog gauge with pressure increments reading 0-5 (0-5000 psi) is prominently mounted at the top of the cylinder. The gauge adjusts to four positions for easy viewing from the cockpit.