When mounting side guiding rails on {HEAD ~ vertical wall surfaces} of {TAIL ~ a building} it is often problematic to correctly align and space the various mounting brackets used in the mounting of a single rail 
When mounting side guiding rails on { HEAD ~ vertical wall surfaces } of { TAIL ~ a building } it is often problematic to correctly align and space the various mounting brackets used in the mounting of a single rail
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH