Trunking 1, in which the first engagement means comprises {HEAD ~ a part circular bead} formed along {TAIL ~ the free end} of each side wall and of radius greater than the thickness of said side wall 
formed along
Trunking 1 , in which the first engagement means comprises { HEAD ~ a part circular bead } formed along { TAIL ~ the free end } of each side wall and of radius greater than the thickness of said side wall
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH