brand Arca compatible Low profile Tripod Ballhead XB-28 Low Center of Gravity Very versatile Jaw opening range of 37.25mm to 41.5mm will accommodate any Arca style plate from various makers including: Really right stuff (RRS), Wimberley, Jobu Design, Arca ., Kirk Enterprises, Markins, etc. Eliptical Ball for progressive resistance. Y-axis diameter 0.03mm longer than the X-axis. Super strong shell. All Metal knobs. For long term durability. Main Lock Knob Scale Ring Laser-engraved with index marks. Pan Lock Knob and Panning Base Scale Independent Pan Lock Knob, 360° panning movement with calibrated precision, precisely capture overlapping panoramic images. Panning Base is laser-engraved with index marks in 5° increments. Ball Diameter: 28mm Base Diameter: 40mm Height: 67mm Weight: 190g Max load: 4.5kg (10 lbs) Bottom thread: 3/8″ with 1/4″ adapter