SUNWAYFOTO brand Arca compatible Tripod Ballhead FB-28i. 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-Swiss, Kirk Enterprises, Markins, etc. 26lb Max load Includes independent ball Lock. Single notch design. Super strong shell. All Metal knobs. For long term durability. 37mm clamp with Bubble level. (offset bubble level LB-01 can be added to 3 mounting points, but is not included) Bottom thread: 3/8" with 1/4" adapter. Ball Diameter: 28mm. Base: 40mm. Height: 70mm. Weight: 207g (7.3 oz). Max load: 12kg (26 lbs). 1 year Warranty.