The Arca Swiss Monoball Z1 sp (Single Pan) Ballhead builds on the success and popularity of their B-series ballheads. Z-Series ballheads are just as elegant and even more perfect. The size and weight of the ball heads have been significantly reduced. The ball and fastening are now assembled using a patented bayonet mount. Various accessories can thus be quickly mounted to adapt the tripod as required. The Z series can withstand an incredible 130 lb (59 kg) off-axis. This model is the sp version which features a single panning base. The Z1 head is also available as the dp version with a double panning design. Ever since their introduction over forty years ago the Arca Swiss Monoballs have been at the forefront of quality and performance. Today their unique shape (an ellipse rather than a sphere) is still what separates them from all others. With other ballheads no matter how good the tension modulation you invariably will need to increase the tension control as you move the load away from the center. This is because gravity has a greater effect on gear when not perfectly level.