Please see the j250-2. It is all about the clamping. Our heads were specifically designed to hold not just weight but fulcrum. That is weight that is on an arm, like a long lens. When clamping anything it's all about surface area and friction. If you look closely, our heads use steal leaves stacked upon each other at a central elbow pivot. Each of the leaves have a surface friction area of about 1 cm and two sides. Twenty four leaves gives you 48 cm of clamping surface area. Extremely strong and rigid!