The Manfrotto 501HDV is not a fluid head, but uses special Teflon-coated discs (used instead of fluid cartridges) to ensure consistent friction of the head. This head features a secondary security lock so you cant accidentally release the plate (and camera) without meaning to. The lock stops the quick release lever from opening fully. A two stage, lightweight, high tensile aluminum tripod that is extremely rigid and stable. The 546 has a die-cast aluminum crown with a built-in 75mm interface bowl, adjustable quick action leg clamp levers for reliability and safety in the field and either a floor-level or mid spreader which aids tripod leg angle setting adjustment. Lowest leg section has twin spiked metal feet. Plastic hook clips keep the three legs of the tripod tightly together during transport or carriage. Spreader included, giving the tripod more stability and rigidity. Leg extensions are locked and unlocked using convenient quick release flip levers. Tripod folded length: 72mm, minimum height 32cm, maximum height 156 cm.