This bolt secures the closing cap on the hydraulic control block of the host tractor. It sits at the end of the valve stack, retaining the internal spring pack and spool components within the block. A loose or missing bolt allows fluid leakage and loss of control pressure to the downstream actuators. This original-manufacturer bolt is threaded to match the block's port and has the correct shoulder length to apply the required clamping force without bottoming out. Torque the bolt to the specified value on installation.