F-550 single-cylinder hydraulic floor spring with replaceable spindle head. Suitable for doors up to 1500 mm wide and 300 kg. Maximum opening angle: 180°. Hold-open at 90°; non-hold-open and double hold-open options are available on request. Installation adjustment: 6 mm in left/right, forward/backward and up/down directions. Two closing-speed adjustment valves: 90°–20° and 20°–0°. Tested to 500,000 cycles.