Gitzo GT1540T 6X Carbon Fiber Series 1 Rapid Column 4 Section Traveler Tripod Ground Level Set: This feature allows you to remove the center column to save weight and get the camera closer to the ground. Uses existing components: the upper disc with reversible 1/4 - 3/8 bolt and the column hook assembly. ALR - A new Anti Leg Rotation system, which means the tripod can be opened in less than 15 seconds. Simply loosen all the twist locks on each leg at the same time, then pull the leg down and tighten the locks individually. Hook: This built-in accessory allows you to hang a stabilizing weight (e.g. a full camera bag or a sand/water bag) from the bottom of the tripod center column. Useful with long heavy lenses, on uneven ground or in windy conditions. Rapid Column: The center column locking collar above the tripod shoulder makes it easier to adjust the column quickly. Series 1 and above are built with an anti-rotation grooved center column for improved stability. Reversible Column: The rapid column can easily be inverted for an alternative shooting angle or low level macro work.