Large Grip Handle. Heavy Duty Design. Quick To FitSWL::- :- 750 kg Tube Diameters: :- 48-51mm. A Standard Doughty half coupler fitted with an easy grip handle. This clamp has a slotted base to captivate an M12 Nut or Bolt enabling users to create fixings suited to their own individual requirements. Manufactured from high tensile aluminium extrusion. Available in Black or Polished Aluminium.. doughty coupler-trussing coupler