Desmond DBH-X1 Ball Head Arca/RRS Compatible w 50mm DAC-X1 Tripod Head with Independent Pan Lock DAC-X1 50mm clamp accomodates Arca-swiss / RRS style plates Independent Pan Lock Knob Oversized comfort grip control knob Ball Diameter: 42mm Includes DP-50 50mm QR Plate. Includes Nylon Case.