The BC2 Conduit Clamp Set will adapt a 100mm (4") Conduit Carrier to a Rhino-Rack Heavy Duty Bar. It comes with 2 clamps and allows for mounting of the conduit above or below the bar.
 
Features:
Allows fitting of 100mm (4") Conduit Carriers to Rhino-Rack Heavy Duty Bars
Recommended maximum carrying capacity is 15kg / 33lb