This National Geographic NGEH1 Expedition Hydrostatic Head incorporates the innovative hydrostatic locking system that produces an absolute rock-solid lock with the small turn of a knob. Using hydraulics instead of a mechanical approach produces a super-tight lock with minimal amounts of knob turning. The effect produced is a smooth moving ball, but when locked, essentially becomes a solid part with the head. National Geographic has teamed up with Manfrotto to bring you the tools that top explorers and reporters trust to help them bring home the best images possible. For the traveling photographer, speed of reaction is crucial, and sturdiness and stability can not be allowed to compromise portability. These products have been designed to combine low weight and reduced size with professional performance. Uses the latest materials for silky smooth operation and its magnesium shell produces feather light weight. Large ergonomic handle with precise friction adjustment. A rubber bellows system prevents dirt and debris from entering the ball area ensuring problem-free photography even in the most extreme locations. RC2 (3157N) Quick release system, supplied with 1/4-20" and 3/8" camera fixing screws. Calibrated, adjustable friction control for stability. Independent pan lock for 360° movement. Independent tilt lock allows for +/- 90° tilt movement.