The two longitudinal members 12 and 14 are each formed of sections of {HEAD ~ hollow cylindrical metal pipe} or tube, such as EMT or other reasonably light weight and suitable material of sufficient strength for {TAIL ~ the purpose} 
The two longitudinal members 12 and 14 are each formed of sections of { HEAD ~ hollow cylindrical metal pipe } or tube , such as EMT or other reasonably light weight and suitable material of sufficient strength for { TAIL ~ the purpose }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL